Force debug in safe mode via USB? I did something so stupid I'm almost kind of proud of it. I rooted my LG Optimus T (Froyo) using Gingerbreak, cleaned out a bunch of stuff, and accidentally deleted the home screen launcher. No big, I'll just install a new one... but I have a chicken and egg problem now, that requires debug mode to get out of. I can't just open settings on my phone to set debug mode. And the phone only starts up in safe mode. 

So the tl;dr is this: I need to force my phone into debug mode via USB, in safe mode. If I can't do this, I will have to buy a new phone. Please help me!
The easiest way to recover your phone is to flash the original factory firmware on it.

After much searching I found a thread at XDA which explains how to do this for the LG Optimus series phones including the P509 (yours).

You can obtain the original firmware by following these directions (substituting P509 which you have for P500).

After you recover, remember that the first thing you should do after rooting a phone is to install a custom recovery (usually Clockworkmod Recovery) as this gives you access to tools to manage situations like this.