So in order to work with SharePoint forms from your blackberry, there are a few tweaks that need to be made to your BB.

First, open the browser on your BB

Second, open the options and select Browser Configuration

Third, check the boxes for 'Support JavaScript' and 'Allow JavaScript popups'

Lastly, scroll down and change the Emulation Mode to 'MS Pocket IE'

That was all the changes that I had to make allow me to interact with a SharePoint site from my BlackBerry. I hope that helps!