Looks like you may already have your answer.

If you are familiar with IR code formats, you could, in theory, separate the non-repeat and repeating parts (see Barry Gordon's document in the Classic Pronto Files Section on Pronto Hex IR Format). You would then have a non-repeating and repeating button and based on what you needed, you'd issue executeActions() on one of these buttons. I've been working with winnipeg300 on something like this using the jog wheel. Have not had much luck with this approach as of yet.

However, there's still hope. (Thanks Peter). Try adjusting the duration of the IR from something other than default to something longer. If this works then please post back.