huh, I thought I had a reply to this message already... anyhoo
My POV project is a small pic on a board with a shift register, and the whole thing is hard wired to a 18650 lithium cell. there is no on/off control, a button puts the pic to sleep to turn things off.
anyway, when it's time to program, I connect all the leads of my programmer, except Vdd. I haven't had any problems doing it this way. Technically it's a no no, since the target is at Vbat and the programmer is at Vusb but I just let the clamping diodes in the target pic handle the level shifting. my target is a 12F683, so it may behave differently than your larger (and considerably older) f876