Rocky,
No, there is no way to modulate the pressure, although it does take a couple of seconds for the brake to reach full pressure.
There is no interlock, so you need to mount the switch in a location where a passenger cannot inadvertently "hit" the switch. Jon Haas used to make an EPB controller that mounted in the bottom switch position, where the blank switch normally resides. I believe he discontinued it for exactly that reason.
I did have an interlock that disabled the EPB switch at any speed above 5 mph but I had an EFI ECU with a VSS connected to it, so it was pretty easy to configure.