I am planning on upgrading my old XT compatible system with a new
motherboard, hard drive, and 1.4 MB floppy.

I am interested in using my old power supply (150 W) to power the new
hardware, if possible.  

I have been told by the motherboard vendor that I could probably
use the supply if it had twelve wires going to the motherboard.
(Apparently some XT vintage supplies had only 11 wires -- the
12th wire is a 5v line used to charge the motherboard battery).

My question is has anybody tried bringing an additional wire
out of an 11 wire supply OR using an auxiliary power source
to charge the motherboard battery?

I do not wish to buy an entirely new power supply if I can 
make use of my existing one with simple hacks.

Thank you for any information.  
An email reply to rarbanas@rcsuna.gmr.com would be fine.