I've found that if you just run very fast, you can usually do it. Sometimes I do get stuck in the large room and have to reload from the autosave and try again. And on the way out once the spiders blocked me and I had to reload from a save (I save inside dungeons in a separate file titled "danger"). Basically, here's what I do:
Enter the tunnel and run like heck for the back. The bats near the entrance can be annoying, but they can also be ducked. The rats and spiders hiding in the side rooms are slower than you are if you just run right in. When I get to the corner that goes into the big room, I don't hesitate, just run down the stairs, dodging anything in my way. This is where it might take a couple of tries. Up the stairs on the other side, and back to the library area. I didn't get hit by the fireball, but maybe I was just lucky because I wasn't trying to dodge it on the way in. The fighter NPCs in the library took care of anything that followed me. Then I let the rats out of the secret room and run back to the corner behind the fighter NPCs, who kill the rats. Then I go in and get the tile and the scrolls. I save the game then and run back out (on the way out, I time the fireball so as not to get hit). I jump off down into the big room (don't bother with the stairs) and land on the other side of all the creatures trying to get me, and then just run out, keeping my eye on the wizard eye map for navigation.
Doing the game this way (low kill), the most difficult place in the game was the Breeding Zone, because you can't do just part of the task and come back to finish it since everything resets in the meanwhile. So I ended up having to kill two gogs in there when I was trying not to kill anything other than the required quest kills.
