as you probably know your bios jumper is under the gfx card, and if you have a sound card you cant fit a screwdriver down there to short it.
so...
take your gfx card out, find a two or three pin plug with corresponding wires like a reset switches wire into the jumper, and then cut the other end of the lead off so your left with two wires. all you need to do now to reset cmos is touch the wires for 30 seconds.
ive just left my wires in opposite sides of the case so they cant touch, but if you can solder you could make a very nice switch or wire it into a button or power reset switch on your case