How can i install a v belt for a Toyota corolla 2005 xrs?

I assume you mean the serpentine belt that drives the various accessories (i.e., water/power steering pumps etc.) and not the timing chain (which some may mistakenly call a belt). If so:1) Working...

It has a timing chain. It never needs be changed.

This should be done by an expert with the proper tools. Severe damage can be done to the engine if it is done incorrectly.

Not sure if the 2005 is the same as the 2006 model but the only way I know is to disengage both airbag plugs under each seat. No beep but also no airbag.

This is a too vague of question. Depends on year and engine type. Some do and some do not.