is it possible to change the default rear view mirror with the mirror with the home link integrated mirror?
Absolutely, although the installation is not for the faint of heart. Check eBay, several toyota dealers have them listed, then price your local dealer. Good luck with the install.
Yes. There are a few ebay sellers that have the mirrors & most importantly the wiring pigtail. Once u get those, u need to tap into the right wires to get the homelink working. I did this on my gen2.