A long time? what's different between an rb20 and a 25? a 25 doesnt take long to do. remove crossover, coilpack cover, coils, injector crank it over.
Is it a redtop or a silvertop? ECCS or NICS?
I'm sorry I don't have the tool Richo but maybe give James from TypeX Motorsport a call:
http://www.rpmlounge.com.au/bdir_typex.php
He's a good bloke, can do anything with any engine. might be able to help you out, but naturally he doesn't work for free. If it's only the tool you need then it shouldnt cost you much.