Options for setting "java system properties" in fuse

Background: I am working on adding inifinispan cache to a webservice of mine that runs on fuse 6.1, with infinispan in "library mode", with a jgroups configuration to cluster the cache nodes for replication using TCP (we don't route UPD on our network). I have it all working fine when I use java command line arguments to set some of the jgroups properties like this:

Question: I'd rather not change the karaf java command line for this...this is a total newb question, but what are my options for setting "java system properties" for use by an OSGi bundle? My preference would be to use something like this from blueprint:

so that this can be controlled using /etc/myService.cfg, but this doesn't seem to work (the property place holder itself works - I can log this property from a camel route - but jgroups doesn't seem to see this property). I've also tried just creating a .properties file in my bundle's resource directory, and tried this from blueprint:

but this didn't seem to work either. I'm pretty sure I must be missing something basic.