Officially there isn't. You may want to google "enable plugins in tenfourfox" and then follow the link to the macrumors forum. This will work up to TFF 17. After that, there is no way whatsoever to enable plugins.
If you mean plugins, then no. If you mean add-ons, then yes. I don't know about official support, but i have most of my favorite firefox addons working fine in the latest TenFourFox on my Dual 2.0 GHz G5.