Thanks for the idea Hobbes; my friend is unwilling to give up the rule book as he just recently purchased the game ;)
Is there a posted rule book that is the next best choice?
Not of my knowledge. But are you familiar with the new rules that came out with A&A Anniversary? That might be a starting point since Pacific 1940 largely uses them (although with quite a few additions).
You can download the rulebook http://www.wizards.com/default.asp?x=ah/prod/axisanniv and afterwards there’s a pinned topic at the top of this subforum about Europe and Pacific’s Facts that describe its features.
Finally you might want to have a look at the posted errata later and ask your friend if he’s aware of it. It isn’t official yet but it is being compiled by Krieghund, who is a member of the development team.
A combination of the AA50 rulebook and Djensen’s rules previews on the A&A.org homepage (and the posted errata if you choose to use it, which you should IMO) should give you everything you need.