I changed these belts today.
Photos of the steps:
1. Loosen alternator adjustment bolts, pivot alternator and remove alternator belt.
2. Removed wheel and the splash guard in this photo
3. Behind the splash guard gives access to the crankshaft pulley and the tensioner pulley for the air-con belt. Adjust the highlighted bolt to loosen and remove the air-con belt.
It's possible to access the air-con tensioning pulley without removing the splash guard in the previous step. Though it might make it harder to route the belt around the crankshaft pulley.
Installation is the reverse of the above steps.
The alternator belt was 4PK890 and the air-con belt 4PK855.
The original alternator belt is made from EPDM so maybe it can go further than 100,000 km though it is only ~$20 AUD to replace.