If you have to ask this, then you need to call the friend back and
tell him to take it to an AC shop.  If you do not know the right base
stock/grade oil, which refrigerant, have a good vacuum pump and
service guage set, then you shouldn't be doing the job.  I guarantee,
if you try this without the proper tools and knowledge, the system
will fail in short order, and take the "new" compressor with it.
Rebuilders are VERY careful about scrutinizing failed compressors on
warranty claims now.  They can spot wrong oil, acetic oil, wrong or
mixed  refrigerant, low charge, poor or non-existant vacuum
pulldown...you name it.  If you want to keep this person as a friend,
refuse the job...period.

More new and rebuilt compressors are sold because of jobs like this
doen in driveways by unqualified people than any other single reason.

whatever you do, don't take the advice of new resident troll,
DESERTBOB- the guy doesn't even know his wrench sizes, and actually
drives an old rotted 1970's Honda car

I would be very hesitant to "backyard wrench" an A/C system. Evacuation
of refrigerant, purging, refilling, all use tools that must must also
be used correctly [usually beyond the average wrencher's experience and
domain].

Give a year, make, model, engine size, maybe I can find a link for ya
to r & r the compressor, but I would really suggest take it to a shop.
The $$ spent would be well worth the savings in time, aggravation,
needed tools, and risk of personal harm.

Not to mention, screwing things up. At least your friend would have
recourse with a shop to get it done right, with you, you could end up
in front of Judge Judy. :wink:

Tell your friend to open his/her wallet and get it done by a shop.

I completely agree with Desert Bob's advice. If you have to ask this
question on Usenet, that's a sign you should just stop.