Do you have evoX yet? If not, I can tell you where to get it, its illegal (look in "the usual places"). If you do, great!
First ,download xboxisotool,
http://dwl.xbox-scene.net/~xbox/xbox-sc ... ol-1.1.zip
Edit: must copy and paste the above link into the address bar, otherwise it takes you to xbox-scene.com main page
Open xboxisotool, select the root directory of evoxdash.xbe (rename it to default.xbe), evox.ini, and other folders (optional). Inside the root directory there must be a large "dummy" file, insert any file in the directory at least 50 megs in size (it can be anything, but a large rar or zip file is reccomended). The dummy file is so that the Xbox DVD drive can read the disc.
Then choose a name for the ISO, it can be anything, and browse for where you want to put it.
Click "create ISO" and it will. Wherever you chose to put the iso it will be there, named whatever you named it.iso.
Burn this ISO to a CD-RW or a CD-R (cd-r only works with samsing drives).
Put it in your Xbox, and reboot it. You should be in evoX now.
Connect your Xbox to a LAN, and it should display an IP address in the "settings" menu. You will have to reboot the box after connecting it to the network.
On your Computer, go into internet explorer and type ftp:\\xbox:xbox@ipaddress <- put the IP address shown on the settings screen here.
Hit enter ,and you will see a bunch of folders, C, D, E, X, Y, Z, etc. Click on "C", and you will see a bunch more folders, xboxdash.xbe, and maybe other files.
Copy all the EvoX stuff to the C drive, including evoxdash.xbe (keep this name), evox.ini, Skins folder, Trainers folder, Bios folder, etc.
Remove the evoX cd (that was just so you could FTP), and reboot the xbox .It should go to the evoX dash now, if not, then your Bios must only search for xboxdash.xbe. Put the CD back in, FTP to the Xbox, look in "C", and rename xboxdash.xbe to msdash.xbe, and evoxdash.xbe to xboxdash.xbe.
Reboot the Xbox, now it should go to EvoX with the chip on, but it will go to an error screen with the chip off.