Try this program:
http://freewareppc.com/utilities/wm5newmenu.shtml
I know it's for WM5 (been using it since my PPC6700) but I've used it through my Mogul and now TP2 running WM6.5.
It allows you to remap and rename the left or right softkey, but better yet, lets you add more apps to launch.
So my left softkey is renamed "Personal" and when I press it, I get a popup and can choose between my Calendar, Camera, File Explorer, and two Internet Shortcuts.
Make sure you soft reset after making your settings. Let me know if it works for you.