Ok Rob, got it all figured out for you. One forwarning though is that this IS the VSS signal, but it's an A/C signal, not an on/off (digital) signal.
Located in the right side of the floorboard there is an area with several connectors. To get to it you'll probably have to remove the right trim on the floor inside the passengers door opening, then push back the carpetting a little, not that bad to do. Under the carpetting on the extreme right there will be a bib black plastic conduit, which should unsnap pretty readily, and you'll see lots and lots of wiring in there. The one you need is called X47. The description of X47 is "Rear axle RPM sensor harness connector (6 pole). OK, I'll try to describe which one it is. The very front connection in the group of about 10 connectors is a very large gauge RED wire terminal (a terminal being some wires with "eye" connectors on the end, all secured together using an insulated stud and nut). OK, so that real big red wire we'll say is #1 (it's the feed to the fusebox and other large consumers in the front of the car, like the starter). There may be a series of studs behind the big red #1, or there may be no more of this type of connector. In the earlier cars there were some VSS connectors there, but the 97 they changed quite a bit, and not sure if there will still be terminals there that WOULD have been used, or if they got rid of them all together. I'm pretty sure there will be one small terminal just behind the one big red #1, and after that there will either be NO more stud-type terminals, or maybe 2 unused ones. After that, you will find a couple more typical electrical connectors (push-together type connections). X47 will probably be the second of this type of connectors. It should have spaces for 6 connections. I can give you some idea how to make sure you have the correct connector by telling you the wire colors:
"Oh shoot" (thinking out loud here), they show an X47 connector 1 and connector 2. Hopefully you can get in there an find out what's up. The one you need is called connector 2, and they say it's terminal #2 on that connector. The wires you need are Green with a Black stripe. On one side of the connector there is one of these wires (from the ETS/SPS control unit) and the other side there are 2 wires (all black with green stripe). The 2 wires-one goes to the radio (auto volume control) and the other goes to the PSE control unit under the back seat (unsure why it needs this info, possibly the doors auto-lock at a certain speed?)
On the X47 connector one, (should be near the connector 2 that you need), terminal 1 is black with yellow strip (both sides of the connector, term 2 is black (both sides), term 3 is white with a yellow stripe (both sides), and term 4 is a white wire (both sides).
There is no dedicated wire to the instrument cluster like I thought, the speed info I now believe on a 97 is fed to the instrument cluster through what is called a CAN data bus (serialized information line).
Also it looks like that green/black wire data is actually fed from the RIGHT front wheel, not the left, just so you know. The info is coming from the ESP/SPS control unit.
If it's easier for you, you can also find the other side of the green/balck wire behind the radio, it may be easier for wiring the unit. On the radio back, it's connector A, pin 1 (again, green wire, black stripe, should be easy to identify.