You can do either hm or int on your gear, hm would be the more effective route if you are going to mainly heal.
Look for: hm on your wep/ armor/ main slot charm, and ee on your heal for your secondary slot.
For you stats, put all of them into int.
To heal others you just have your heal charm selected and click on their character.
Healing mage guide:
http://forums.d2jsp.org/index.php?showtopic=34945092&f=272&st=0