bypass cmos battery

On most mother boards there is two or more pins that look like jumpers close to the battery. This is where you would plugin a battery that you would buy from a computer store. Try going to ibm web site and look up your user book for that computer. It may show and tell what kind of replacement you need.
www.ibm.com

Considering the cost to doing a work around,which does not seem to be an option

I would suggest that you look into purchasing a new case,because they are pretty cheap right now and it would not be that difficult to transfer your hardware to the new case

While many older motherboards that used NiCad batteries to back up the CMOS had headers for a replacement battery, the newer ones with the Lithium Coin cell sockets usually do not have a battery header.

If you are referring to the coin cell battery holder, the safest option would be to solder fine wire (28awg) to the remains of the terminals, and wire them to a new battery holder mounted to the chassis.
Be sure to watch the polarity very closely.
Also, unplug the power supply from the wall.

If you can remove the motherboard, and get it to someone who is a VERY GOOD electronics solderer, they may be able to replace the socket without damaging the board.
The person doing the soldering must be familier with working on multi-layer boards.

Chas