create a dummy spell based on channel, make its stats such as you want them, write a trigger based on event "Unit starts the effect of an ability" condition: it's the right ability, action: set temporary location at the unit casting the spell, create a dummy unit at the temporary location, add Raise Dead to the dummy unit, order dummy unit to cast raise dead. Add a short expiration timer to remove the dummy unit after it has time to only cast once, then remove the location leak from where the dummy was created.
Do a forum search for dummy units and leaks if you're not familiar with the terms.