PharaohsVizier is correct although I believe R4 saves should be the same as EZ saves in this case (the game uses 4MB Flash if I recall) so could you not just use the EZ4 (assuming it is not an EZ4 lite compact) to run the rom and use the GBA link features of that.
As for the EZ3 linkup I had a theory but never got any feedback on it (and probably will not from this thread) but using a trimmed rom as the loader (and passme2 functions for saves) could you not fake the presence of a GBA game.