Not ResEdit, because it's not a resource. But you could probably use a hex editor like FEdit.
I edit the ROM data file on a Windows computer, using the free hex editor xvi32. Then I copy it to the Mac and update the ROM-inator's flash memory. The happy face is stored beginning at offset $FD2 (hex) in the ROM code file. It's 20 bytes long (16 x 10 bitmap at 1 bit per pixel).