using 1.2.4 and s2 together

[Asthana, Rahul]

Hi All,
We have a fairly large application, with about 500 actions.We have a release 
every 6 months in which about 50 actions get added. We are currently on ver 
1.2.4 but want to use S2.Is it possible and feasible to use s2 only for the new 
actions that get added(probably use a new extension?)? What are the possible 
issues?
TIA
Rahul