May not be the most efficient way to solve this but...:
In the script; firstly split the Invoice field in to its parts using something like left(Invoice,index(Invoice,'/')-1) and so on to give you a table (Data) like:
ID | Invoice | InvoiceA | InvoiceB
1 S200 M250 R35
Now perform a Concatenate load from your table back onto your table something like:
InvoiceA as Invoice
Drop Field InvoiceA;
Repeat this for InvoiceB and C, D, E or as many parts as you have.
That should result in the table you need.
Alternatively: you can at this point perfom a Cross Table load to achieve teh same effect (see the Help file).
The script hasn't been checked.
Hope that helps,
Matt - Visual Analytics Ltd