I know that a pencil will work, but I've read a lot of different posts where the pencil didn't work, causing much fiasco and consternation. If you have a KT7 mobo (I do) you cannot take the CPU HSF off while the mobo is installed. Wait, lemme rephrase that you can take it off but good luck trying to get it back on! The problems with the pencil trick are due to different pencils having different graphite contents, therefore their electrical conductivity is questionable.
I used a conductive pen. The "nib" is too big for connecting those microscopic bridges, but I took off the end (unscrews) and dipped a sewing needle in the ink and used that. It is a pain in the butt and requires a very steady hand, but it's permanent and well worth the expense ($15) for the pen.
BTW, no matter what you use, you will need a magnifying glass.