At some point you always need to have an internal maven repo. Currently we have with closed source database drivers at http://reports.qa.atl.jboss.com/jdbc-drivers/maven2.
Put files in a Repo
To put files in a repo you have to use the maven deploy:deploy-file mojo/whatever. Use a command like this below and tune parameters as specified in the the pom.xml. For the url you can use scp and ftp also.
mvn deploy:deploy-file -Durl=file://<path to repo> -Dfile=<file> -DgroupId=com.oracle -DartifactId=ojdbc14 -Dversion=10.0.2.0 -Dpackaging=jar -DgeneratePom=true
See links section for more details.
Use a repository
You have to modify user's settings.xml or specify a custom one for the build process. Details to be filled in.