Not sure that another thread is necessary for the performance/scalability discussion. It's kinda ingrained as an aspect of this use case, right?
On a somewhat related note, I'm concerned about thread safety. Gut first reaction to support what you want would be to have another action (or a property of this action), which specifies the a combination of the original ruleProperties (which is how we cache stateful sessions today) PLUS an entry-point name perhaps? The problem with that, in my mind, is synchronization, as stateful sessions are not thread-safe. In BusinessRulesProcessor, we currently lock() on access to the cached session. To have multiple actions being executed by services in different threads lock on the same stateful session is not very condusive to CEP applications, where Very High throughput is expected.