At the moment you have to call fn.caller.arguments in the token function to get the logging event information.
Logging event should be passed in as an argument or in the context.
Definitely will fix this one - I'm currently fixing up the code to use strict mode, which stops you from using fn.caller (I think), so your workarounds will break.
This should be available now in version 0.6.7 in npm. If you could confirm that it does what you want, that'd be great.