Some months ago I replaced a leaking nicad battery on a 286 motherboard with a cr2032 battery and holder (the battery holder fits the old holes perfectly).
I cut the positive power track and inserted a small signal diode to prevent charging the non rechargeable battery. It worked for a time but the voltage was borderline for the CMOS/RTC chip due to the .6v drop across the diode.
I Also found the battery very quickly goes under voltage so the fix leave a lot to be desired. 

Just recently picked up some schottky fast recovery diodes in a pack on ebay for fixing power supplys. The FR107's in the pack can't handle more than an amp so are no good for power supplies.... aside from fast switching they have another very desirable attribute, they have a very low forward voltage drop.
So today I thought I'd replace the signal diode I used on the 286 board with one of the FR107's. Measuring the forward voltage drop it is now only .09 of a volt... far better than the .6v of the general purpose silicone diode I had been using.

So my tip is if you are going to replace a nicad with a CR2032 battery on an old board use a FR107 and not a general purpose diode.