programming avr from another mcu

I’m too cheap to buy a dedicated avr isp programmer when I have a perfectly good ethernet enabled lpc2119 with some extra 3.3v pins and flash.

Anybody know where I can borrow some simple code or wiring recommendations to get me started, or what kind of serial dongle to emulate with a tcp socket and modify an avrdude driver.

New to avr and I only want to play with the attiny84/85, and I only have a modern usb-only linux machine so the simple lpt and bitbang serial programmers are out.