It should be possible, though I haven't actually done it. Basically you'll have to go in to the actions.txt and edit it manually. I can't remember exactly how to do that, but there should be some information in this thread or in my animation tutorial that will help.
Searching (with Ctrl+F) for words like "slashright," "ready," "release," and "continue," should help you to figure out the actions.txt too.
Edit: You'll also need to have the right .brf files in the resource folder, and tell the game to look at the CAE file by fiddling with the module.ini. I think I've explained how to do that stuff elsewhere.