Hi SnowStorm,
If you have already an answer to your question, ignore my reply
Below link has an information about how to deploy Guvnor 5.4 on glass fish 3.1.2 step by step.
http://stackoverflow.com/questions/14160138/steps-to-deploy-guvnor-in-glassfish
If you have deployed Guvnor 5.5 on glassfish 3.1.2 , let me know as i have issues in deploying and launching it , thanks in advance