Kind of a strange request, but I think it is workable. it just seems like it would make your device act like a provider bridge instead of a customer bridge. And that would require that you would have to change the ether-type to be ether-type 0x88A8 and configure the trunk port like the provider bridge. At least that is my understanding of how trunk and acess ports work in this type of network environment.
set ethernet-switching-options dot1q-tunneling ether-type 0x88A8
lab@EX-4200# set ge-0/0/x unit 0 family ethernet-switching port-mode trunk
lab@EX-4200# set ge-0/0/x unit 0 family ethernet-switching vlan members [v1 v2 v3...etc] or all