Well, I have gone through all RoCo I – VII and reviewed SUC. I find nothing to imply that one could use power projection to drain power from a spell.
When I played RM2 (we are now playing RMC with just what has been released – I am using old Creatures & Treasures though), we had created a skill based on Power Projection that allowed power points to be drained from items, persons (contested and very dangerous to both parties), and the land itself. I did this because I had created a spell shaping skill that allowed the casting of spells without list or learned spells and it required very large amounts of power points and was extremely dangerous. I did this to represent how magic started (spell shaping), grew (Arcane) and evolved (Realms).
I said all of that to say that you might be able to create a skill based on power projection that might be able to drain power from a spell, but it should be hard, contested and very dangerous.
If you want the rules to the other skills that I created, let me know.
And, lastly, no, as the rules are in RM2, you cannot drain power points from spell using Power Projection.
