Grab the version bundled with modmii, it's the latest one... I'm not sure if it will resolve geckocodes issues though, but certainly it will be newer than what's in this thread.
For cheat codes, if the latest version doesn't work, either use a different loader, or try Modmii's cheat code downloader (downloads page 2) - warning, this could take awhile
Edit: nikeymikey, if I recall correctly you were pretty active back in the day... by this I mean your nick seems vaguely familiar to me even after all these years, lol