Ed,
You could get around this by modifying the snowdrop module definition - e.g. by creating an ehcache module and adding a dependency on it.
On the other hand, If you have a simple WAR and do not need the functionality of the Spring deployer, then you can simply deploy the war as a regular application, leaving the ContextClassloaderListener to do the bootstrap. Just make sure that your war has all the classes that you need.
Hope this helps,
Marius