How to replace front seatbelt

My dog chewed my front driver side seatbelt. I have one on order, and was planning on having the dealer install it, but was wondering if how hard is it to install it myself. The dealer charges about 250 in labor alone they claim they have to disengage airbags and electronics. Is this true, I can't seem to find any instructions on whats required to replace the seatbelt. any advice or links to instructions are greatly appreciated

 

I bought one of the PDF service manuals and reviewed it, doesn't look too complicated to fix. is there anything to worry about when disconnecting 12v battery? looks like I just need to open and close the power window to initialize it?