This is the alternate path for finishing King's Quest VI. It won't get you as many points as the optimal path, nor the best ending, but it's worth playing through, particularly if you've already beaten the game by following the long path.
Getting a Suitable Lamp
Now that you're back on the Isle of the Crown, it's time for you to get into the castle. But you have a couple of things you need to do first.
For one thing, you have a white rose that you'd like to send to Cassima (assuming you picked another one from the rose bushes on the Isle of the Beast). Go to the tree at the fork in the road and USE the white rose on Sing Sing [1]. Sing Sing will fly off, and a brief cutscene will play where Cassima tells Sing Sing not to return to Alexander so as not to endanger him. Hmm, nothing else from Cassima? Well, hopefully you'll be seeing her soon enough. Head to the village and enter the pawn shop.
It looks like the genie is hanging around, disguised as an old man again. Wait, didn't Jollo suggest that you try to convince the vizier that you'd died? The Drink Me potion from the Isle of Wonder will allow you to fake your own death, and with the genie here, this is a golden opportunity. Assuming you picked up the potion, USE it on yourself in the pawn shop [3]. Alexander will very dramatically announce that he's killing himself with poison, drink the potion, and seemingly "die". The genie will be delighted, and head straight off to tell Alhazred the good news. Play close attention to the cutscene that follows, as it'll tell you something very important, namely what the genie's lamp looks like.
After the cutscene, Alexander will come to, leaving the pawn shop owner somewhat bemused at what just happened. The only thing left to do here is to get the nightingale: you'll need it in the castle. USE the tinderbox on the pawn shop owner, and take the nightingale. Leave the shop.
By happy coincidence, the lamp seller from the beginning of the game has returned to town, and just when you're ready to trade him an old lamp for a new one. USE the lamp on the lamp seller, and he'll give you a selection of lamps to choose from. You now know that the genie's lamp is blue, with a round base and a tall, thin neck. Use the HAND on the lamp that fits that description (it's the second one from the right) to take it [1]. The lamp seller will walk off, but not before rubbing the lamp you gave him. That one's a dud, but yours isn't: with a lamp that's an exact replica of the genie's, you may have a chance to acquire the genie's lamp and become his master.
Entering the Castle
It's now time to make your way into the castle. Walk to the castle, and you'll see a number of serving women entering to prepare for the wedding. Alexander's not the type to dress in drag ordinarily, but desperate times call for desperate measures, and you happen to have a way to disguise yourself as a serving woman. USE Beauty's clothes on Alexander [4], and he'll duck into the hut nearby and change into Beauty's clothes, after which the guards will let him into the castle. Apparently the guards paid no attention to Alexander walking up to the castle, since they didn't seem the least bit suspicious about him walking out of the hut in women's clothes. Nor did they notice what a manly-looking woman Alexander is. Maybe the guards really are as dumb as they look. But that's good news for you, as it got you into the castle.
Once Alexander gets into the castle, he'll quickly get rid of Beauty's clothes and change back into his regular apparel. You're now in the main entry hall: there are two staircases you can walk up. Go up the left staircase: if you walk up the right staircase, you'll be caught by the guards, and your game will be over.
Distracting the Guards
Once you get to the top of the left hallway, you'll quickly duck behind a wall to avoid some guard dogs, and overhear their conversation. Apparently Cassima has been begging to be let out of her room, but the guards are under strict orders to keep her "safe". They aren't very happy about keeping her locked in against her will, though. They also mention that the vizier is offering a reward for her missing nightingale. Of course, you know where Sing Sing is, but trying to collect that reward is probably not the best idea.
After the guards finish talking, they'll stand with their backs to you for a second, and then come back down the hall. You can try and make a break immediately for the alcove on the right side of the hallway, but you're likely to be caught. It's safer to wait for them to come down the hallway, and then head back again. Once they're nearly to the other end of the hallway, it's safe to head for the alcove. WALK directly to the alcove, and you'll enter it. If you do get caught, restore and try again.
Once you enter the alcove, you'll get a message saying that the guards are coming back down the hallway. Immediately use the HAND on the pillar to hide behind it. The guards will walk by, but they won't notice you. They'll then walk back the other way and pass you again. After they do so, immediately WALK into the hallway, and USE the nightingale on the carpet [4]. The guards are looking for a nightingale: maybe this will fool them. Hopefully these guards are as dumb as the ones outside.
Once you've used the nightingale, immediately WALK back into the alcove, and use the HAND on the pillar to hide behind it. If you've timed everything right and haven't gotten caught by the guards, the guards will come and investigate the nightingale without noticing you. After a brief discussion, they'll decide to bring this nightingale to Captain Saladin on the off chance that it's the one Cassima is missing. Thank goodness for stupid guards. The guards will then head downstairs, giving you time to explore up here. Don't waste any time, though: you only have about 5 minutes of real time before the guard dogs return.