The vitalist begins with the Collective Healing ability:
Whenever a willing member of the vitalist's collective could regain lost hit points or ability damage, the vitalist may choose to redirect any or all of that healing to one or more other willing members of the collective as a free action. This can transfer instantaneous healing (such as a body adjustment power), healing from ongoing healing effects, such as fast healing, and even hit points gained from rest (in which case, a member of the collective would rest for a period of time as normal, and the amount of hit points and ability damage healed would go to another).
In any case, the original recipient of the healing effect chooses whether to allow the diverted healing, and does not gain the benefits of any healing he grants to another. The type of healing (positive energy, negative energy, construct repair, etc.) is unchanged from the original source for determining who or what can be healed.
Example: Darius the soulknife is a willing member of Jorus the vitalist's collective. He drinks a potion of cure light wounds that would normally heal him for 6 hit points, but Jorus decides to redirect 4 of those points to himself. Darius agrees and, as a result, Darius is healed for 2 hit points, and Jorus is healed for 4. If there were more members in Jorus's collective, Jorus could spread the healing from that potion out even more as long as the sum of hit points healed was no greater than 6.
A vitalist may even heal wounds through collective healing if at full health. This may only be used with healing effects such as potions, powers, or other such effects. [Healing] from long term care or natural healing cannot be transferred in this way.
Say that I am missing 4 hit points and get a Cure Light Wounds cast on me that rolls 8 hit points worth of healing. Can I send the extra 4 hit points to another party member?