Oof, I'm with Shade.
Ok, I think this is going to be messy, but I have a proposed plan.
1) Write a gaseous or incorporeal monster (at this point, I'm ceasing to care which

) with an infusion special attack and phylactery type object (though why a golem would need a phylactery is beyond me, what a weird monster!). Am I missing any special ability here?
2) After infusion, rather than a modified alternate form/change shape, apply a template to the character "infused" to create a duplicate. This should have a "Con countdown" SQ. I vote that the "blood drain" or whatever it should be called should be a touch attack with a "do not notice" ability. We can flavor it to be incorporeality, but make it a normal touch attack mechanically.
Sound ok?