You need to put one chip on each of the two RAM chip nearest the CPU (no particular reason for thair pair - it has to be a side-by-side pair though as each chip covers half the databus).

You need to bend up the CS pin on both of these chips and wire them together and to the 4th DRAM bank select pin on the CPU. Sorry, I'm at home and don't have the datasheets on my laptop so I can't be more accurate about which pin numbers... I have pictures of mine to upload too...

I'll try to remember to do this tomorrow.

Hugo