I have been googling and searching in this forum, and it seems the only way to have a counter on screen that's not related to time, you'll need to manually make stills for each and every number and place these manually on the timeline.

In other words, first I need to make...

1.psd
2.psd
3.psd
...
100.psd

Then import them all as stills, and then place them where I need them

Sounds like a really tedious job. That's no problem though, unless someone knows of a more effective way of doing this!