This has probably already been done but there were a few tips and tricks i wanted to put out in case anyone needed any help. I will go over the driver seat as the passenger seat is pretty much the same process.
This tutorial was done with a NA base 1998 V70 with no original wiring for the driver side power seats. The wiring was already in place for seat warmers and the passenger side had wiring for power seats.
Foreword: This tutorial will leave you without SIPS airbags. Now that may be a big deal for some, however i had no personal reservations about it given a previous crash i was in (insert the sips in action thread). I put most of the text in the photos due to laziness.
Link to the SIPS post: topic92753
Fuse 39 = driver power seat.
Note I just routed the wire under the passenger seat and to the driver seat. You can put it under the floor, however i just put it as close to the centre console as possible. I zip tied the excess wire to the moving part of the power seat.
Conclusions: If you do not have the driver side wiring then do not sweat it, get the connector and tap into the passenger side wiring. Alternatively you could try the accessory connector, and wire power directly from there.
I disconnected the battery before doing all this and had no issues.
Good luck
)