Flash that Sony Ericsson K800 into a K810 {Engadget Mobile}

Sep 26th 2008 6:11AM Hello
I have Sony Ericsson K800i but my phone is sometime down the firmware and software. Therefore i go to Phone Repair shop and do that. but i don't want to repair phone service shop and i want to do myself to repair. Please explain me.
I want to know if my phone is down again how to do myself. I check website and some of people say, i need to Universal Box for that repair. This Universal Box is very expensive i can't buy. Therefore no need to repair for Universal Box. Please explain to me step by step.
Please Help to me.