Haven't tried it yet. If you have 7B85 why not try it yourself? ThemeChanger was working for me in earlier builds. I first ran ThemeFur to make the theme's extras.rsrc compatible with Panther's. Then applied the theme with ThemeChanger. I made sure though not to let it try to replace out-dated resources (can't remember which ones right off the top of my head).
Old themes are known _not_ to work with Panther yet. All themes will need to be updated, as Apple has changed some widgets and behaviour. Look at the tabs in System Preferences for example: Totally different. I suggest _not_ to try a Theme Changer for a while, until a theme creator has verified his updated themes working fine with this or that theme changer at least.