Hello Murat,
SunMC 2.x and 3.0 currently don't support NAT (that I'm aware of), but 3.5 is nearing release and I'm almost certain NAT support is on its feature list. Read more here:
http://wwws.sun.com/software/solaris/sunmanagementcenter/sunmc35.html
Perhaps your Sun representative can get you access to the beta distribution?
Regards,
Aronek
Standard disclaimer: I am an employee of Halcyon (www.HalcyonInc.com)