custom dispatcher / AppEngine

I want to use seelog in a package that I want to use on AppEngine and other apps.
I would like to set a logger like explained in https://github.com/cihub/seelog/wiki/Writing-libraries-with-Seelog

I would like to set a logger with a custom dispatcher which writes to the appengine.Context.Criticalf/Errorf/Warningf/Infof/Debugf() methods.

Is there a way to provide a custom dispatcher to a logger?