Well, start off playing around with the one ability that, in a way, does what you want it to: Resurrection.
Resurrection isn't like Animate Dead. It actually fully revives units it cures. The problem is, it's an AoE non-targeted ability centered around the hero. So you can't choose which corpse to revive.
Anyway, try setting the maximum number of targets revived to 1 instead of 6, so you only revive one character. Then, set the AoE range a lot lower than default, like 100 for about melee range. Make sure the only targets allowed are friendly heros, and then implement the trigger I gave you. This is the result:
You have a hero, Mr. Reviver. Mr. Reviver's friend has just died to creeps, and you want to revive him. So you go stand on his corpse, and you click the button for your new custom ability, Revive. Assuming that the friend you are trying to revive is the only friendly hero within range (which is why the small AoE range, so you can be precise) you should revive the hero, at which point the trigger will immediately give the newly revived unit to the player that originally owned it.
If you want to target this ability, then I can't help you. Finding a targetted revive ability is hard enough without the confounding problem of figuring out how to target corpses.
Hope this helps.