Like i said earlier there is no easy answer or automated way of integrating CATS into service Manager.
Before getting into technical implementation of CATS into service Manager :-
a) Do you know what is the use case your trying to address ?
b) Service Manager allows to enter time/labor for service products during SO confirmation. Does this feature adequate to meet your requirement ?
c) How are you planning to use CATS functionality in Service Manager ?
d) where are the time entries posted ?
e) Is required configuration for CATS time entry in in place in CRM/ECC ?
f) How is personnel number linked or used in CRM ?
g) Does CATS functionality provided in WM 6.1 meet your requirement ? if not better to develop your own Agentry screens/ java code and by using reusing SAP BAPI/class handler code of CATS.
You can use WM 6.1 jar files but all the variable names and naming convention should match with CATS java code including SAP config. panel entries. It is hard to tell unless you get into specifics.
Once that is finalized then you need to maintain proxy system connection in CRM system to execute BAPI relevant for CATS in ECC system , import CATS Agentry changes from WM to SM , port Java code, publish changes to SMP server.
Thanks
Manju.