I\'m currently working on two projects simultaneously:
If OSS project has dependencies - create a POM with those dependencies (your project will use them as transitive dependencies) and install that artifact and pom in local repository. If OSS project hasn't any other dependencies is even simpler - the POM is generated automatically during installing.
For both cases use maven-install-plugin.
mvn install:install-file -Dfile=your-artifact-1.0.jar \
[-DpomFile=your-pom.xml] \
[-Dsources=src.jar] \
[-Djavadoc=apidocs.jar] \
[-DgroupId=org.some.group] \
[-DartifactId=your-artifact] \
[-Dversion=1.0] \
[-Dpackaging=jar] \
[-Dclassifier=sources] \
[-DgeneratePom=true] \
[-DcreateChecksum=true]