We're using the WAR implementation on a few sites with Apache Tomcat and TinyMCE. There's snips on how to get SnipSnap running, so I won't go in to that.
The steps above will work, the compiled main.jsp (main.class) is in the snipsnap-jsp.jar and contains the tinyMCE.init call. You may want to try removing the old main.class file and unJARing the snipsnap-jsp.jar. Otherwise, you could add the tinyMCE.init (pluginSnip.txt) call to your main.jsp yourself. Of course you'll need the source distro of SnipSnip.
I'd also recommend checking your app server and JavaScript log to diagnose any configuration problems… ;)
Having said that, my partner came up with a simple and easy (hack) that provides most of the features of the TinyMCE WYSIWYG - table editing and all - but we just didn't have the time to do it right by converting HTML to SnipSnap Wiki syntax and back. Since the SnipSnap authors seem to be missing in action, we needed a good but temporary solution till we find a decent migration path. Of course we still have hope that a true WYSIWYG to SnipSnap syntax editor will be created (maybe using TinyMCE), or the authors are resurrected and SnipSnap continues to be enhanced.