rooting - How to root HTC Desire (Froyo 2.2) without putting in a custom ROM (flashing)?

for research purposes I'd need to root a HTC Desire phone without flashing it. I did it already on the HTC Hero, where it was quite simple.

Basically all I would need is to get r/w access to the /system/app folder for copying my custom apk file there. Obviously this needs root access.

Is there a way to easily root the Desire without the need to completely flash and place a custom ROM on it?

Some details about the phone:

• OS: Froyo 2.2


• Software number: 2.12.110.4


• Kernel version: 2.6.32.15

Thx for your help

Answer

Unrevoked 3 will root the HTC Desire without replacing the ROM, however it does reflash the recovery ROM: http://unrevoked.com/#desire