How to change ISO on G1X?

Hi everyone, this is probably a really stupid question with a very simple answer, but...

I just got my G1X a couple of hours ago and have been playing with it a bit... and I can't seem to find any way to change ISO manually outside the 200-1600 range.

In other words, I am for example in P mode (I tried the others too, including M, it's the same everywhere) and when I press the ISO selector (upper part of the selection ring), I am shown Auto ISO with the 200-1600 range selected/selectable and all other values dimmed. I can set ISO manually in that 200-1600 range but I can't select ISO lower than 200 or higher than 1600.

I've tried the menus (can only find the place where to set the maximum for Auto ISO) and various modes, and I read the bit on ISO in the manual, but... I just can't seem to find any way to get out of that 200-1600 range.

Help!