Any way you want to.

It's gonna be slang in any case, and that gets spelled in lots of ways. If it becomes as common as gonna, it'll develop a normal "eye dialect" spelling.

You could argue for at least the following possible spellings, as communicating the syllable /yuʒ/: youzhe, youzh, yuzh, uzh, uzhe. They all have their problems, and only the ones that work will stick. So try'em all out. This is the way the language grows.