Vista - Logging Application Block - Modify settings in code?

I'm trying to use the Logging Application Block system in the MS Enterprise
Library.
All my settings are defined in the config file and everything is working
fine.

However, there is one setting that needs to be dynamic dependent on the
environment where the application is currently running
I have added a listener, and I need to be able to modify the "url" paramater
of that listener in code.

Can this be done?

Thanks,
Kim