Use incense on torch, you'll have a piece of incense with smoke coming from it.
Use lit incense.
If nothing happens, then sleep.
Regardless of that, you should sleep after having slain the evil wizard, if you haven't already.
As for the Bullfrog puzzle... you don't have to complete it properly. It's just a means to an end. You can use any other means of expedited movement available. But what you're looking for on Level 5 is easily accessible from whereever on that level.
In other news, with the added info provided here, I was finally able to get both games running with MT-32 music. And with the SVN Daum build, I even get them in fullscreen on a 16:10 screen! Thanks again, everyone!
There's only one problem... I don't like having Roland sound in UUW1.
The music sounds brilliant, but as many have pointed out, there's no volume control on it, so it drowns out the effect sounds. And turning off the music in UUW1 is not only robbing you of one of the best soundtracks ever made for a RPG, it also left me with the realization that the MT-32 sounds, while better than the Sound Blaster/Adlib noises I had grown up with, are also too loud. I ran down the first hallway, stopped, listened, and could hear the rat moving about in its room to the west. Through a closed door. And 5 feet of stone. I re-installed UW1 from scratch, and am now playing the game with the standard Sound Blaster/Adlib configuration that I had all those years ago. I'll download the soundtrack in MT-32 format from somewhere for my own enjoyment later on. But right now I'm about halfway through the first floor and I'm already at Level 5. I gained a level just by walking close to the Green Goblin King. Weird. IIRC, I was Level 9 by the time I finally descended to the second floor the last time I played.
Meanwhile UUW2 works brilliantly, with the digital samples complementing the MT-32 soundtrack wonderfully. I rolled a high Strength Druid and named him Garrett, because I was suddenly reminded of one very interesting fact: All those items in the castle that do not belong to you, are being left unattended at the start of the game, because almost everyone has gathered in the throneroom for a meeting. I'm gonna play this game with the notion that every item that isn't "belonging to a XXX" belongs to me, and the other items will soon belong to me. I'm gonna raid the other worlds for everything of value and fix the Britannian economy all by myself!