Other then the risk of electrocution, it ought to work.
One of the things Ilike about 12V radios is it hard to
get killed working on them. I operate all of my
radio gear from a +12V Lamda supply.

If you get across the EL driver in the 2004, it will bit
you, but won't kill you, or at least it didn't kill me.

I would be sure to put a label on the ouside and inside
warning of this mod.

I bet you driver trasnsitor died. In the '2004, it is Q701
and is a 2SC945QA, or the dimmer switch opened.

The '2004 and '2005 are very similar, I would guess the
'2006 is also.

Terry