electric power mirror puchase/installation

I purchased a 2004 Chevy Express van that did not have electric
remote control power mirrors. I would like to purchase the entire
assembly and have it installed, replacing the manual side mirrors.
I have not been able to find the entire assembly, only the power
mirror assembly. Can anyone tell me where/how to find the
entire assembly which would include the interior remote control
swtich? I read a similar discussion that stated that the door panel
would need to come off to connect the wires. Any additional
installation information would be greatly appreciated.

Thanks,
Kathy