If the mic is happy with a 9V supply then yes, in theory, if you
wire up an
adapter properly it will work, although I can't say how long. You could just take a 9V battery clip from Radio Shack and
wire it to a male
XLR connector, and also
wire that in parallel to a female (basically, the battery clip is ending up as one side of a Y).
In fact, on the Rat Sound website, they note how in a pinch you can use the Rat Sender part of the Rat Pack test set as a phantom supply by Y-ing it in
line with your mic, since it's basically just a 12V battery wired into an
XLR connector as a phantom supply would be.
It's not the best solution in the world, but in a pinch it'd work if the mic is happy with that low a
voltage. I'd be afraid of it dropping below a usable
voltage pretty rapidly, though, especially if 9V is already at the low end of the usable
voltage scale. You might see about wiring two or three batteries in series, perhaps, to boost the
voltage, or if it does work well on 9V than in parallel to increase the longetivity.