I found this in a search:
https://desk.surpasshosting.com/pda/ but it's only available for staff (internal use). According to the post, someone asked Support about it, and they were working with the software vendor to allow public access. No updates came after that, and it was in July 2006.
I started a thread at some point about getting a mobile theme for the forums, because I would use it all the time on my phone, but I can't seem to find the thread now. I know there were a few people that liked the idea, and I think Dan said he would look into it, but I never heard about it again.
Depending on your Blackberry you should just be able to go to the normal URL and get to the helpdesk without much issue. That's what I do on my Windows Mobile smartphone and it works fine. I just have to scroll around on the screen a lot.