Never heard of poured pillars before, but the idea sounds interesting. If I were to go about it, I would turn down some action screws/guidepins. they would have the correct threads for the reciever and then step up to a larger diameter then step back down to the normal size. The larger dia. part would be as long as the distance between the reciever and the bottom metal, basicly it would set the "pillar" length. Drill out the stock as you would to install pillars, clamp the reciever lightly in the stock with it upside down, apply a good release agent to the stepped screws and thread into the reciever (I guess that you would thread them into the reciever before putting it into the stock as that would be easier and you would want to coat the part of the reciever that the bedding would touch with release agent also) Then pour the holes with what you're going to use, clamp the bottom metal on using the guide pins to allign, It should come to rest on the stepped portion of the guidepin. When it's all dried up remove everything and you should have a pillar with a hole that's not going to touch your action screws. If you can measure everything up AJ, shoot me the dimensions, and I'll turn you down some guidepins, only fee is that you have to report back on how it worked out. Let me know.
Zeb