RGMII interface over gxb channels

Hi guys

i will use cyclone iv gx and i was wondering weather it is possible to interface tse altera component (generated by mega wizard) over gxb pins. As you know rgmii has 4 tx and 4 rx pins (plus rx/tx clk and rx/tx "controll") and works as ddr. I want to use on *_p pins (no *_n pins) of the gxb transceiver channel. Do i still need altgx or not?

regards