LOL. The BlackBerry IS a Java OS!
I don't know Myspace, but first, use your Internet Browser, not your WAP Browser.
Second, when you're in the Browser, click the wheel and select Options, then Browser Configuration and make sure you have all the Java and Script options enabled.
Finally, if I remember correctly, Myspace does not work well with the BlackBerry Browser, but Opera Mini works much better. Install it OTA here: http://www.operamini.com/
(It's also in my Mini Version Tracker list)