[Preston Pilot 47472]

Can anyone recommend a way of motorising the Airfix 1804 Richard Trevithick plastic model kit?
What I would like to do is construct 10ft of flanged track and run the loco with a couple of scratchbuilt wagons so the intended model won't be the usual two rail electric fed as the wheels will be plastic.
I have a couple of discarded "Thomas" battery-operated locos which I thought of cannibalising and incorporating in some way.
Any ideas?
Thanks.
David.