Aggregate/Concatenate Strings In A Script Component?

Hi--

I am uncertain how to do this. I am thinking it could be done in a script component, but after a day of experimentation, I'm not getting any closer. I'd also like to know if there is another component I may be able to use for this.

I have data coming from an Excel Spreadsheet that looks like this:

CustNumb Invoice
1 a
1 b
2 c
3 d
3 e
3 f

I would like an output that looks like this:

CustNumb Invoice
1 a, b
2 c
3 d, e, f


I am not even sure if I should be trying to do this in the subroutine that looks at each row or the one that looks at the entire buffer.

Thanks for any help or ideas...
Hilary