I've just stuck a pair of Recaro Sportlines in my MY00 Classic. I didn't have the original (Prodrive?) harness to make the connection so took a feed direct from the battery. I didn't think that this would be an issue as our other Subaru has electric seats that operate without the ignition switched on.
I've just popped out and noticed that the height adjustment switch is illuminated! Not wanting to drain the battery I've just removed the fuse for now but where could I take a feed for these seats that is controlled by the ignition.
Does anyone know where the connection was made when Prodrive offered these as an option?

 

Have you any idea what sort of power they consume? The current draw?

If it were me, I'd power them via a relay. Buy a 4 terminal on/off type, preferably with a fuse incorporated, but if not, see later.

Now run a cable from an ignition live, eg: the radio, to relay terminal 85, and another from relay terminal 86 to earth.

Using decent thickness cable, according to the current drawn, connect from battery +ve to relay terminal 30, via a fuse and holder if your relay doesn't have a fuse. Finally take the same thickness cable from relay terminal 87 to the seat.

All my electrical stuff comes from: Vehicle Wiring Products Ltd. Suppliers of auto electrical parts.

 

Wow. Thanks, that is very helpful.