I'm not sure that it's good idea. It is much easier to encrease existing connection pool limit. I know that Oracle has special method setMaxLimit(int limit) for it's connection cache implementation. Try to search something similar in JBoss.
I tried to increase the pool size with the attributes from the ConnectionpoolMBean (XADatasourceloader). But it really has not any effect when the pool is running.
So I'm looking for alternatives to increase the size.
But with two XADatasourceloaders there is the problem:
Server.run/init: java.sql.SQLException: The database is already in use by another process.
Has maybe somebody any effort increasing databaseconnectionpool during jboss is running?