Yup. It works. Though you probably have to use USB Loader GX or, preferably, CFGLoader. I don't think WiiFlow supports many ocarina codes that is required for Project M.
To get it working, all you need to do is get the homebrew version, open it up and drop the files into the root of the SD card, install CFGLoader, and allow Ocarina codes and set hooktype to VBI. Finally you can launch the game.
There is a channel forwarder that automatically launches Project M through CFGLoader with ocarina codes straight through the wii menu, though you gotta rename a couple of folders and install the .wad file. Other than that its really easy to install.