Is there some documentation on TinyWiki? Is it actively maintained?
As it says in the mail you reference, SmallWiki (and therefore TinyWiki and PicoWiki) has been discontinued in Summer 2004. SqueakSource is one of the last users of one of these packages, there might be some updated versions in http://www.squeaksource.com/ss.html. However this is code that only works in Seaside 2.6 or even older.
I suggest that you use Pier. I do that for many of my projects. Pier can be easily embedded into any application, as well as you can embed any application into Pier. For simple wikis it might be a bit overkill to have to load the whole code-base that is more a CMS, so it would probably be worthwhile to have a simple Seaside component that just reuses the document model.
Cheers, Lukas