Hey, I'd be willing to take a look at it for you. I'm not familiar with that Zelda engine, but I'll see what I can do. A long time ago, I made a game that had dashing when you held down a key. I could look at what that code was and see how it would fit into your system.
OK, I found the code. Lemme just post it here and you can see if it'll work. If you still need help, I can do that.
(Edited to remove code, it didn't really work that way >.< But I did manage to get it working, in case anyone was wondering

)