My scala/sbt project uses grizzled-slf4j and logback. A third-party dependency uses Apache Commons Logging.
With Java/Maven, I would use jcl-over-slf4j and logback-classic so that I can use logback as the unified logging backend.
I would also eliminate the commons-logging dependency that the third-party lib would let sbt pull in. I do the following in Maven (which is recommended by http://www.slf4j.org/faq.html#excludingJCL):
<dependency>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
<version>1.1.1</version>
<scope>provided</scope>
</dependency>
And the question is, how to do the same with sbt?