Your friend can't log the hours as P2 as a VLA is not a multicrew aircraft. So if you were logging time as P1 then he can log nothing.
Yes you can log time in the RHS as long as the aircraft does not require the commander to be in a certain seat. Many aircraft do. Instructors are a separate case and you have not led us to believe that you are an Instructor and this was an Instructional flight.
I would however question if you were actually insured to be commander, from what you have said I would suspect that you were not if the insurance company required your friend to occupy the LHS for insurance purposes.
Aside from the issues discussed above and to answer your question, you do the 12hrs in the last 12 months, 1hr Instructional flight and then take a completed SRG1119 to an Examiner who will check your licence, logbook and medical and sign the rating.