This works but there may be a better way but this is the only one I know. Hold caps lock and end call button at the same time. You may have to do this three or four times the first time you do this. You will be taken back to the home screen so you will have to click back to your message. To unlock caps hit the caps key twice. Hope this works for you.
Posted from my CrackBerry at wapforums.crackberry.com