I have it working with a little library.
There are 2 ways:
1. (clr-reference "Twain.NET, Version=18.104.22.168, Culture=neutral, PublicKeyToken=null")
2. (clr-reference Twain.NET) ; no string, no extension, no quote
I just tested and confirmed both these cases work. What does not work, is when the assembly is not found, and it is suppose to signal an error!
Just some other observations.
1. Is the assembly in the same path as IronScheme.dll?
2. Are there other non GAC dependent assemblies not in that directory?
To get point 2 working (assemblies from outside), you will need to modify the app.config to specify additional 'binary load paths'. This is a standard .NET thing, and not IronScheme specific.