I've done it before. Connect a loop start trunk port to a single line station port. Create a phantom ext and do a manual forward of the phantom to dial trunk group, pause (or two), then page code. So, assuming trunk is 92005 and you want page zone 0 you'd forward to 92005PP70. But as you say, security is an issue...so you might try leaving the second P and 70 out of the forward string and requiring the caller to dial the 70, maybe even change page feature code to more digits, for example 74835-0 so caller can't stumble on it. It's been a while since I did, so my memory might be foggy, let me know if you have trouble and I'll fool with mine again.