You need the datalogging cable for a 2g which plugs into your Palm. Which plugs into your Diag. Port. Atleast thats how mine was when I had the datalogging equipment and software for my 1g.

So pretty much you need:
Palm Pilot (forgot which models work)
Serial Port Cable
Datalogging Cable (plugs into the serial cable and your diag. port)
Datalogging Software

If there's any wrong or anything I left out then someone correct me but thats what I recall when I had the Datalogging Setup/Equipment for my 1g that I was running this on.

It should be fairly simple... pretty much plug and play. Palm then serial cable then datalogging cable to diag. port. Thats how mine was setup on the 1g.