Are Session Beans extendable?

[markus . karg]

We are developing a standard software basing on J2EE Session Beans. The problem is, 
one of our customers needs a small change in one of the SB's methods. We
thought of inheriting from our SB, only overwriting the "default" implementation of 
that method, and then telling JOnAS not to load the original but the
inherited SB. Is this possible? And what about calling extended functions (calling the 
super SB's method implementation)?

Thank you for every tip!
Markus