My wife agrees that I can buy another Agestar to hack and use the other one for our network storage. With this new Agestar I can continue my hacks. Currently I am working on building a firmware that can be used to install Debian without serial port. On the first stage, I will build a generic firmware without automatic installer, so the user still needs to do some manual steps to install Debian. So it is something like the manual Debian install on NSLU2 (http://www.cyrius.com/debian/nslu2/unpack.html). Actually because this is generic command line, you would be able to install Gentoo or something else. The next step would be to make an automatic installer like in NSLU2(http://www.cyrius.com/debian/nslu2/install.html).
The main reason why I started with manual installer is because I am not yet familiar with the Debian installer. Currently the manual installer is almost complete, I just need to test it thoroughly to make sure that this will really works without serial port. I hope I can release this in the next few days (or this weekend at the latest).