Sorry to disappoint but I think you'll have to write the tutorial yourself. Unless I've missed something, IronRuby doesn't run Rails yet, although they've demonstrated some aspects running.
According to the IronRuby home page they're at about 71% complete on the RubySpecs core package, which is probably still some way from enough to go from rails <projectName right through to ironruby script/server
When IR runs Rails, I think we may hear about it. Or rather, we may have to shut ourselves in isolation chambers to avoid hearing about it...
