I think it's safe to say that if you don't have a real serial port (ie - a desktop serial port, not a laptop or a usb-serial adapter), you might as well forget about using a JDM. You might be able to find the some way to make it work with some "band-aid" circuitry, etc, but you're pretty much guaranteed to endure a lot of headaches in the process, and probably still won't end up with a reliable programmer in the end.
There are other options out there, ie - parallel programmers, PROPER serial programmers (that don't draw power from or otherwise abuse the serial port), and USB programmers... JDM serial programmers are almost invariably the cheapest option, but they're still a waste of time and money if they simply won't work for you because of your computer hardware, so you might as well look into more suitable options, even if it costs slightly more.