Church Corner-Stones

I recently received a call from a dear friend of mine asking if I knew anything about any customs regarding church corner-stones. He had been told on good authority by a priest that there were certain rituals--perhaps only in the Extraordinary Form--regarding the laying of a church's foundation-stone, and that specifically a sort of interior corner-stone, hollow, was traditionally placed at the Gospel side, where the apse intersects with the wall of the nave, and that documentation and dates were placed within it. I told him I'd check my copy of O'Connell when I returned home this evening but I figured if anyone could shed light on this matter, it would be our readership. Thoughts, anyone?