WD20 - input mask for time > 24 hours

Hi,

I need to input times with hours more than 24. Say an employee worked 123:45 this week, then I would like to enter this value.
The reguler time mask HH:MM is ment for max 23:59 time values.
I'm not a regexp export. Can anyone give the regular expression for this, which I can use (in with a normal edit-control).