It's pretty easy.
Just run a p2pool node and let your friends connect using their payout address as username.
If you really wanna charge a fee for your "friends" take a look at hte p2pool wiki:
-f FEE_PERCENTAGE, --fee FEE_PERCENTAGE
charge workers mining to their own bitcoin address (by
setting their miner's username to a bitcoin address)
this percentage fee to mine on your p2pool instance.
Amount displayed at http://127