Serial Port programmer of AVR is not so hard. You can use the same software PonyProg to load HEX to chip. It needs a change in the interface setup section. I will tell it, lets see the circuit. there are many circuits of serial port ISP available on net, I am going to the simplest one to make thing easy.
by Miroslav Batěk is really good one. He used the same circuit i have given, I am uploading the pcb he made for the circuit.
His PCB looks like
His complete device looks like
You can find the circuit here also,
or other Serial port programmer,
I have tested all these, no doubt they work.
First one will easier for you. Components list of first one,
I used the second one for sometime. here it is,
My first programmer was a serial port programmer(not for AVR), designed by Pi Labs (by Masum Habib Sir, Razib Mikail Sir and Shohag Vai). The programmer was for 8051 family as far as i remember. On that time I learned to use software "Keil" and "FLIP" from Pi lab. I have lost totally what other IC's can be programmed by it except, At89c51Ed2. Infact i didnt continue with that chip too much for a long time. but no doubt this board had many provisions.
Use of PonyProg: I guess you read the parallel port programmer section so you should familiar with ponyprog. To use communication port you have to change the Interface section. here it goes...
Then select micro, open device file and all are same.
I always appreciate to use dedicated programmer from manufacturer. Try AVR dragon