In fact, development of tihs programmer was quite easy. I took sources from tuxgraphics and wrote new low-level layer for PIC device. There were some platform dependant things in protocol layer sprinkled all over the shop, so I corrected it. I divided things into two main groups - protocol layer and hardware layer, separated into two .c files, unlike original sources with many source files.
Hardware is quite simple - programmer is powered from target application, so level converters are not needed. There is no ESD protection on programming lines, just straight IO pins of PIC. User have to be careful, but I'm planning to use it a few times and then forget it, so no problems.
There is not much to say about it. It works with AVRStudio (on Windows) or avrdude (Windows / Linux), as fast as other AVR serial STK500 programmers.