from the updated client go to c:\program files \comman files\symantec shared\virus defs
you will see a dated folder which has the latest definitions, copy the contents of that folder; it will be like 201104003
create a folder called incoming on the machine u want to update the defs
c:\program files \comman files\symantec shared\virus defs\incoming
paste the contents of 201104003 folder inside incoming folder
wait for a min it should be udpated