GPS In Sun glasses holder?

[Igg]

Hi All, Long time lurker here.

I finally made the foray and got an 2010 SL AWD.

I'm thinking about permanently mounting a garmin nuvi into the sun glasses holder.

One thing that's holding me back is the power source.

I know that you can tap in some where right there by the dome light etc but unsure as to which exactly.

Second. Would I just tap into the power spot with a female socket so the standard garmin power can be plugged into it?

Thanks for the help.