I can't figure out what the heck to do about the mustard slimes on the 3rd floor of the Dragon's Eye. I've checked the walkthrough to the level posted here but it is pretty vague on what to do:

"just deisarm the trap on the floor on the room"

Well, I can't find it - plain and simple

Can someone step up to the plate here and offer some sound advice?

Alright, there is a room where you click on the walls and it says you need special tools to circumvent a time lock. Take a rogue or someone with an appropriately high search skill (I had a 19) and search towards the top section. Just stand there a minute or two with your search on. Then disarm the red pressure plate that appears on the ground.

what if i don't have anyone with a very high search skill - my rogue is focusing on traps and pickpocketing - not search - what then?

There is a priest spell called "Detect Trap". Ranger, bard and paladin probably can learn it too.

Even though I think it's pure idiocy to go dungeoning without a rogue type even if multi-classed out the whazoo, I do have to say the game designers were mean by putting things like this in here that can be near impossible to complete without one.

Those slimes are vulnerable to fire.

fire spells, fire potions, fire-tipped missile weapons, fire producing melee weapons.

FIRE IN THE HOLE!!!