Erg. Gr./JG 54 had an emblem in 1941/2 consisting of a Viking ship in full sale on a shield with a white (? need to check) ground. This was retained when the unit formed 3./Erg.Jgr Ost in April 1942.
If this is the one you mean I think their is an image in Ketley's 'Luftwaffe Emblems 1939-1945'. I can have a look tomorrow.
Cheers
Steve