The Bookworm achievement is simple in theory but somewhat difficult in practice. It simply requires locating the torn journal page 8 times in the playfield (max apparently of once per session) and clicking on it. Each time this is done unlocks another page in the journal, do it 8 times and the achievement is complete.

The catch of course is:
1) There is a random chance to spawn (seems to be ~33%)
2) The location it spawns (if it does) is random
3) Nothing says "please farm points off me" like rooting around in squeaky doored lockers for an achievement item

I found torn journal pages in 3 different locations, however it should be noted that the locker locations were 6/8 of my Bookworm achievement finds.

By far the easiest way to go about this is to play private matches and simply agree with your opponent beforehand that the main hallway is off limits until all the lockers have been opened and checked (because your friends would surely never screw with you by ambushing you while you're carefully searching in an obvious place... right?)

I did this in public matches (perhaps because I am completely insane) so it can be done, but it requires some tactics to accomplish. Depending on how quick you are at picking the correct tactics, it may not even impact your winning the match that much.

Any quick perusal of the spell list should suggest some things you can try, but here are a few that worked for me:

• Early Bird Gets The Lore: You've got about 40 seconds after the match starts before your enemy can really do much to you unless they are completely mental and like fireballs. Unless you're up against an experienced player, they may not even think to look for you that early. It is very hard to check all the lockers in 40 seconds though.
  
• TRAP ALL THE THINGS: This is a tactic which can also keep you from falling behind in the match unless your opponent can adapt to it. Simply trap all 4 doors into the hallway. A map where Fright Pocket is available is great for this, since it's a one-rune spell. Have a spell prepped and ready to go, and if any door trap is triggered, scream your opponent (if possible) and then immediately retrap the door. A skilled player will adapt to this by using Dispel or Hopscotch to bypass the trapped doors, but this usually buys time. Keep in mind you'll have the whole hallway's worth of runes to work with!
  
• I Got My Scry On You: In any map where Scry is available, have that prepped at all times while you're looting. The moment you are the least bit suspicious that your opponent may be investigating, pop Scry. If nothing else they'll probably run hide in a corner, giving you 15-30 seconds of good looting time.
  
• No Fear, Cavalier: If your opponent likes to ambush you in the hallway, and the map supports casting No Fear, well, totally do that. It's only good for a few seconds, but by now you are an experienced locker looter and don't take all that long, right?

The journal of an un-named student attending Little Springs back in the storied, ancient days of 1991.