Using timer(s) to capture multiple inputs

Hi, I read this page with interest: http://www.espruino.com/STM32+Peripheral­s.

I followed the "Counting edges" section and got it working - very happy.

I'd like to capture 3 inputs using this method. Is this possible using more channels on TIM1? Am not clear how pin A8 gets associated with TIM1 CH1 and how I'd do this for other pins. Any pointers would be appreciated.

EDIT: TL;DR
Completed project write up here: https://github.com/jugglingcats/pulse-co­unter

Thanks,
Alfie.