I strongly suggest building a programmer that does not attempt to use the RS232 voltage as a VPP source. It is neither hard or expensive to come up with a external source for VPP.
When you get one of these simple programmers working the first thing you should do is use it to program a chip for a ICD2 or PK2 clone. They will program all but the latest PICs and provide debugging too.
But anyone who can afford the $35 + shipping should just buy a PK2 from micorchip direct and be done with it. For about $10 more you can get the 3 which is what I am now suggesting.
That makes me a bit nervous collin. The RS232 voltage is somewhat of an unknown. I would be much more comfortable with a transistor switching a regulated source. Or at least use a volt meter at add just enough cells to get a correct VPP.
Firstly the 15k limits the current to 1mA and the Vpp line is not critical to over-voltage. You can adjust the 6v supply if needed. Some chips need over 13.5v to "open-up," so you really don't know what voltage you need.