Buy a proper ISP instead.
USB to parallel converters aren't a true parallel port, and so "bit-banging" the USB parallel port to program the 1284 (or any chip) won't work.
There's are a whole heap of cheap USB ISP's available from companies like Freetronics (in Aus), Little Bird Electronics (in Aus), Sparkfun or Adafruit.
Note: I help maintain the forum for Freetronics - though I don't actually work for them or get paid to do it.