I cannot imagine any macro doing what you want. You could construct an IR code, that would do a certain number of repeats, but I doubt that is what you want.
But I can tell you, you don't have to wait much longer. NetRemote is supporting repeats very good, and will be released soon.
I have had the chance to test a prerelease version and it performs great.
They recently changed their website to www.promixis.com
. Just have a look. The Pro version is what you will need. Just have a look. There is also a great forum there...