Transcoding SJIS HTTP post parameters

Hello all.

I am in a bit of an unusual situation and was wondering if anyone has
done this before and have any tips.

I am using rails as a web-app and an API. I have been told that the API
needs to accept HTTP Post requests with SJIS (A Japanese text encoding)
parameters instead of UTF-8.

Since I have no experience with this (Need to do some testing) I was
wondering if anyone could offer some advice / gotchas (Need to see how
rails processes parameters and if it mangles them in any way if not

On a sidenote. SJIS contains some funny characters which usually get
mangled when converted to UTF-8. Can anyone speak up for the
effectiveness of ruby’s transcoding abilities?