In Guvnor, each asset (rule, process, dsl, etc.) has a unique URL that you can use to retrieve its content. Guvnor also keeps a binary (compiled) version of each package containing all its assets that also has a unique URL you can use.
So, in order to get the "source code" of a process "Test" in a pacakge "TestPkg" you can use this URL: http://localhost:8080/drools-guvnor/rest/packages/TestPkg/assets/Test/source
And to get the binary representation of package 'TestPkg': http://localhost:8080/drools-guvnor/rest/packages/TestPkg/binary
Alternatively, you can also use the new Change-Set editor in Guvnor 5.4 to create a bundle of processes that you want to use together: http://docs.jboss.org/drools/release/5.4.0.Beta2/drools-guvnor-docs/html_single/index.html#d0e1703
Then you need to add the definitions and/or the packages and put them into a KnowledgeBuilder. Please refer to the documentation to see how this can be done: http://docs.jboss.org/jbpm/v5.2/userguide/ch04.html#d0e655