add event page - sorting of list of categories

Hi,
My client has many categories of events, and has lower end users submitting events via the front end.
As such he would like to list the categories by category item number sequence - instead of alphabetically.
How would we do this? Can it be achieved by a template override?

Surely it could be implemented using override, but it will quite difficult for a normal users. Maybe consider paying us a small fee (20$) for implement it for you?

Tuan