Just a note: Rivvolution can support unlimited filesize in files (theoretical 16gb max) - however, the Wii has limited space in RAM, so only so much can be loaded at once! How much exactly depends on what is going on.

If the alternate file loader code is simply allowing to hotswap during play, then you can accomplish that through riifs, by simply renaming the replacement folder before you load. Slightly less convenient than pressing some hardcoded button combination, but thems the breaks.