Well it took longer than I'd hoped but I finally deciphered the hex codes. I though I'd write a quick note for the benefit of anyone struggling as I was..

Took me a while before i realised that each burst pair defines Nx0s and Mx1s with the duration of the on and off bursts defining N and M , i.e on for 11 = 0, 31 = 00, 51 = 000, then off for 31 = 1, 51 = 11, 71 = 111 etc with the hex numbers increasing by 32 (in decimal) for every extra digit.

So: 0031 0051 0011 0071 = 00110111

lucie_fear's Excel sheet from the 'iMon HTPC Integration with TSU7000' thread was a big help... once I understood it :)

I've generated clean codes for all the buttons with repeats and they're working well.
Getting the repeat working for the pad was a pain. A note for anyone else trying.. the code needs to be repeated twice in Burst Pair Sequence 1 and just once in Sequence 2.

Anyway, to all who have posted about the iMon, thanks for the help.