Bill,
I'm happy to hear that you have joined the happy pronto users.
Your original remote may be sending a string of the same code that is required for teh standby mode. I should think that the easiest way to accomplich this would be to simply make the pronto macro also have a repeating string. I'd try two, then three, then four and so on until i had a long enough string. It is also possible that your original remote simply has a delay built into that particular key such that it sends NO codes until after "X" time of keypress. A little experimentation on your part in teaching the key to Pronto should provide the desired results. Watch the learning mode indicator as you teach other keys versus the standby key as this may be an indication of when IR is actually being sent by the standby keypress/hold.