I'd second hacking out the front of the case (not the plastic facia, just the metal bits down in front of where the hard disks are, below the floppy disk (I presume...)
Then, you can easily mount a fan in there, I'm going to be mounting a 140mm fan in my case where 4 80mms can fit, i'm just going to rip out all of the metal grill crap down there (already ripped out two of them from the 80mm's i had there) and i'm looking to suspending the fan, = no vibration. I've already got one hard disk suspended in front of the 80mm intakes, and the other is in an enclosure.
Meh, anyway, definately rip the front to pieces 😀 It's fun. Depending on the look you want, if any, either use real man tools like a dremel, or just get a pair of pliers and go crazy.
I'm expecting to easily be able to suspend my fan, initial thoughts are with elastic lace tied between the hard disk mount things and the front of the case, but either way, where there's a will, there's a way.