How to Add multiple time values in HHH:MM:SS format?

Hi,

I need to add a number of time values which might be in either h:mm:ss or hh:mm:ss or hhh:mm:ss formats. I have used aqconvert.StrToTime() to convert strings to time format and then added them which works for h:mm:ss format but has failed when total hours add up to 3 digits (hhh) and also for values in other 2 formats. I guess there's other way round to work this out. Could any one suggest simple vbscript function or TC built in function to solve this please.

Thanks in advance.