Is there any way to script directly to a field repetition using a loop and a global field (where the # of the field's repetition is obtained from the global field, which starts at 1 prior to the loop and increases by 1 during each loop), rather than by definining each repetition manually in the script itself? If not, is this fixed in v. 7? Thanks for any help you can give!

No, but you can put a repeating field on a layout, make sure you can tab through all its repetitions sequentially, and create a looping script that goes to the next field and sets it with the required data, without specifying the field to be set. Here's an example.