Yes, I'd read that thread already as I was searching for how to replace that.
Dell was wanting to sell me a new PDA

I like the fact that I can buy a plug-in solution, but the price is a bit pricey for an old outdated PDA. Combine that $40 with the $50 I just spent on the wireless card... well, that would be a good part of a new PDA that just does what I want. Thus, the soldering method seems to be beckoning. Been a long time since I soldered something. Not sure if my hands can be that steady anymore.
However, it sounds like maybe you are wanting to set up shop and premake these plug-in batteries yourself. If that is the case, I will be your first customer!