[originalscottyg]

How is your friend recording? Is he using Pro Tools? If so, the easiest way would be to send him the whole session, have him record his part into the same session, then send the session back to you.

If your friend is not using Pro Tools, then I would suggest bouncing each track separately without the click track, by muting the click track, soloing each track one at a time, and bouncing. Then unmute the click track, solo it, and bounce the click track as a separate track as well. Make absolutely sure that you don't change your in and out points when bouncing each track plus the click track, so they all can all be lined up at the same place and play in sync.

Hope that helps.