I have seen repeated references to ESP on later Omegas, this is not the first time, so probably some 02-03 models had them...?
See also my other post http://www.omegaowners.com/forum/YaBB.pl?num=1179267753
'ESP for All Six-Cylinder Omega Models
One of the biggest advantages of the Omega has always been the DSA (Dynamic Safety) chassis with its self-stabilizing geometry, which keeps the car under control even in tricky braking conditions. In November 2001, all Omega models with a six-cylinder engine will have ESP as standard, which can increase the safety performance of the DSA chassis further still, especially in critical situations. TC Plus traction control, operating via the brakes and engine, is integrated in the ESP and works both under deceleration and acceleration, also prevents the rear-drive wheels from spinning or locking.'
Mine is May
DSA - didn't that come in with the Carlton?
Mine is June
But is seems that the EPS went the same way as the 2.5TDI and the V8.... missed a turn in the corridor at Russelsheim and never made it into production...