I've changed oil in many a boat engine that way - on my last boat I mounted an oil trasfer pump in the bilge and connected it so all I had to do to change oil was turn a valve and flip the pump switch. It was a heck of a lot better than trying to suck it out through the dipstick.

Some of those pumps like Jabsco are fairly expensive, though - why I recommended a cheap 12v fuel pump...My initial idea was to use one similar to this:

Electric Fuel Pump

I have a similar one that I find a use for from time to time.... it should have no trouble with thin A/T fluid.

There are also hand pumps that can be used..... you could even set up a siphon system with some tubing and a hand priming bulb from a boat fuel system... like this, but cheaper is probably available from WalMart:

Fuel Line

If you use the siphon line, you'd need to reduce the tubing size.

Frank