Right we've managed to spoof dice rolling into working. Type the following.
[roll]1d100[/roll] [roll]1d100+10[/roll] [roll]1d100-10[/roll]
The first will roll a d100, the second will add 10 and the third will subtract 10. You can only roll a single d100 per post it seems and you cannot change it from d100 to d6. The code wasn't reading the input options properly and we don't know why, this at least let it work. The number after the +/- is up to you (doesn't have to be 10).
Note: Only the last dice roll in a post will execute and it will re-roll if you edit the post unlike myBB. If they reply within 5 minutes and their post is auto-joined (double post thing) then only the roll in that second appended post will work.
I will endeavor to fix this better at a later date, for now be glad it works ^^