Well Evox DO make a bios and their current one is the M7. They also make a dashboard and 3921 is the latest release.
What mod chip do you have?
If your machine boots up and under the green X it says xecuter2. This means you already have an X2 bios flashed on your chip (don't know which one).
To put Evox on your box, you will need to:-
1) Create an iso file containing:-
evox.ini
default.xbe (you will need to rename evoxdash.xbe)
2) The evox.ini will need to contain your network settings.
3) Use Simplex to make the iso
4) Burn the iso to a CDR-W with Nero
5) Boot Xbox with CDR-W
6) FTP into your Xbox
7) FTP over:- evoxdash.xbe; evox.ini & the skin folder to the root of C.

Edit evox.ini to how you want it setup.
This guide
http://www.xbox-scen...vox-install.php is worth the read.
XBoxgeek.