I talked to Scottrade and they say that if you own a margin account (and, thus, signed a margin agreement), there is no way to make it so that your shares are unable to be borrowed -- this was seconded by someone else with another brokerage, can't remember who it was though.
For steps on how to set a high limit GTC order, you can see my post #130345 -- it goes through what I had to put up with to get them to make it. Be aware that I've heard of people who got flat out rejected also, I believe they will only do this (and reluctantly, at that) if you own a large enough position, or if you have a large enough account.
