Just wanted to post my experiences getting a v1 WRT55AG flashed with OpenWRT for the first time.
I'm new to OpenWRT and read conflicting reports of OpenWRT working and not working on the WRT55AG. It was an extra router for me so I decided to just give it a try. I downloaded the openwrt-brcm-2.4-squashfs.trx firmware and used the built-in Linksys web admin interface to upgrade to OpenWRT. It worked the first time.
After that I installed X-wrt and have been off and running ever since. No problems. I'd be happy to answer questions about it for anyone with a WRT55AG. But of course if you try it and your router bricks, I assume no responsibility.
Ryan