You don't need the outlet close by. You just need to run some thin wire like the stuff that is run to your garage door's wall switch. 18 to 20 GA wire should do. Connect that wire from your magnetic reed switch to the powerflash module wherever you have it plugged in. Though the DS10As are wireless, you need the OnAlert plugin to use them in that fashion being that the DS10A is a security module.
In my setup, I have 3 modules, one universal module for door activation, and two powerflash modules for door detection. Though many in here only have one powerflash in their garage door setup, I have the two, one to indicate that the door is up, and one to indicate that it is down. I did this because sometimes, for reasons unknown, one or the other powerflash modules would give a false indication in AHP (e.g. a sensor would not toggle). So now I have my macros set up such that when I close the door, if the "garage door up" sensor did not toggle off, when the "garage door down" sensor triggers, it automatically tells AHP to trigger the "garage door up" sensor off. It is the same scenario if I open the door. Having the two PF modules for me is just a fail safe mechanism.