I used PCFE for splitting the "sliding" images of planets from a non tracking DOB into 400x400 pixel centred BMP's which were then loaded into Registax.
PCFE standard settings allow for it to determine the centre of each FOV (ie the planet) and therefore provide you with ALIGNED versions of the planet, Registax can then process these easier.
Try PCFE, there is a link on Mike Salway's Planetary Processing guide article
here.
Take a read of the article, its here
http://www.iceinspace.com.au/63-306-0-0-1-0.html
Cheers
Chris