Ref 3 field in Mass Change in FBL3N

Hi

I am trying to pull in the Ref 3 field in the Mass Change option in FBL3N. The path for Mass Change in FBL3N is Enviornment> Mass Change> New Values. The basic idea is to populate the Ref 3 field with some value for a large no of line items. I cannot use the text or assignment field in this case. Is there any setting for Mass Change wherein i can pull the Ref 3 field?

Hope i get some ideas from u gurus.......thxs in advance.......