I’ve been trying to figure out the protocol for the Abbott Freestyle product line. I made a protocol description which can be found here.
If you’re looking for the description for the Abbott Xceed product line, Chris Ridd made an awesome description which can be found here. He also made an implementation in Objective C, but I haven’t found time to test that.
Abbott sells an adapter cable which uses the TI 3410 chipset. This chipset is supported by most modern operating systems, however not all include the Abbott vendor id/product id (0x1a61, 0x3410 respectively). Currently it should work by default in Windows XP using the driver Abbott supplied, and in OpenBSD since this commit. Getting it working with other operating systems should be trivial.