It is very easy.  You will need one socket on a breaker-bar to grab the
bolt that mounts the pulley to the idler just so you can rotate &
unload the tensioner.  15mm if I remember right.
The belts slip off & you simply wind a fresh one on the same way.
There is also a picture of the routing in case you loose your way.

Check all the idlers (& there are a pile of them) for slop while you
are at it.