Seats that don't use the memory module use direct power from the white wire and a white/black ground that goes to the switch panel. The way that is wired, the switches close the motor circuits and change the way it flows which obviously changes direction. So, you would want to wire it up as shown on page #1023.
With memory seats, the white wire goes to the module as well as two other feeds and an interlock. I remember when bmxrush was trying to retrofit his in, there's quite a bit involved as far as rewiring. In this method, the seat switches are inputs to the module(they don't handle motor current) and the module is connected to/powers the motors, whereas in the non-memory seats, the switches simply do this. The memory module layout is shown on page #1019 of the DI book. Here's a link.
https://www.dropbox.com/s/nji5xr398lz7mio/2001-05 IS300 Diagnostic & Wiring & TSB Manual.pdf?dl=0
You can make a seat equipped with the memory function work without the memory function, but you have to wire all the motors to the seat control panel rather than to the seat memory module(as they are wired now). So really, you only use that white and white/black wires only for regular operation.
Hope that helps.
