Hm, out of curiosity I just looked at the scourcebooks "Forgotten Realms Campaign Setting" and "Player's Guide to Faerûn", and as I understand that's definitely not the the way it's supposed to be (I guess that IS the scource for the feat / PC in the PRC ?) :/. Due to those books "Inscribe Runes" pretty much works the same as "Set Traps", though there also is the possibility for the caster to activate the rune by himself if it contains a beneficial spell. I don't have links to the rules since I own the books and have no need of searching them online (would probably an illegal scource anyway I guess) but if needed I could post them here.
My guess is that "Inscribe Rune" has been confused with the ability of the PC "Runescarred Berserk" to activate his runescars, though I admit I don't know if that PC is part of the PRC ATM :/.
Edit: I just testet runecasting using the PGC3v4.4 and it worked fine for me. Using the feat createt a runestone in my inventory which then I could use like a wand, targeting wherever or whatever I wanted. So the runes don't work like traps (which they would according to the p&p rules) but I guess that wouldn't be possible to implement. Don't know if this helps though :/
Forgot to mention that I use PRC v.3.3g, not 3.3hrc1 though -.-