You'd probably first have to apply some of Mario's physics from the Shoshinkai build. Such as replacing the triple jump with the spinning jump when bouncing on a Shy Guy, a different, lighter ground pound, and the upright run. You'd also have to find the placeholder Mario sounds (I think they're all on YouTube somewhere.). Then you should start off with the iceberg stuff, like Luigi, the brain diagram Wet Dry World, and the Bowser Room (I don't know why this is a part of the iceberg when it was literally just something Chris O'Neil made up when he was a child).
-------------------- Creator of Luigi's Meme Mayhem and Pokemon Crystal Version - Dunsparce Edition