I do not quite understand the notion "outside /standalone application ".
Do you mean you want to use the WAS connection pooling utilised by an application that is not running on that instance of WAS? If this is the case, you may be out of luck :-(
The WAS proprietary connection pool is set up as a resource serving those applications hosted by the application server instance. The pool is managed by WAS, and each application hosted on that instance can have an association built to any of the data sources. I am not aware of any API (or similar) that would open up the pool to external manipulation.
Then again, I may misunderstand what you want to do here. Also, I have not worked with WAS 5 yet. Things may be different there.
Cheers,
Julius