Don't know if you solved this, but it was pretty straightforward today on my 2005 Vogue. You just need to pop out the glass part of the mirror (careful about the mirror heating power cables), unscrew the plastic cover (the one with the bulb sign ), then you have to push the hatch that keeps the light housing in place from inside. You'll need something long and thin to push it as is's a bit deep in the mirror. A little push downwards using your finger should pop the light housing out of the mirror.
The problem I'm experiencing now however, is that the LEDs I installed get immediately shut off as soon as they gradually light up to the full brightness. Seems like it somehow baffles the car's electronics and I'll probably need to install some resistors. I'll keep you posted if you're interested.