Years ago, when the BIOS battery (which is similar, if not identical, to the one for the R50) in my ancient ThinkPad T22 died, I was able to squeeze a CR2032 cell holder into the chamber where the battery sits. I had to cut away some of the plastic of the retainer to make it fit. I used the wires and connector from the original battery. I held the cell holder in with double sided tape.