The latest R4 cart kernel update (1.13) has the moonshell app with it. I'm guessing here, but you might be able to unRar it and just take the 'moonshl' folder and drag it onto the root of whatever card you use for your DS. My apologies if this won't work, just trying to help.
The R4 update is here:
http://www.r4ds.com/download-en.htm
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