How can I boot NIOS from EPCS for Cyclone III with Quartus 10.0?

When I configure CIII in Quartus 10.0, I can't set the DCLK, ASDO, FLASH_NCE as regular I/O in Assignment->Device. DCLK can only be selected as "use as programiming pin", and the other two can only be "as input tri-stated". If I connect the pins of NIOS2 EPCS_Controller to them, I always receive "Error: can't place multiple pin" during complie->fitter step.

It seems that in EPCS_Controller, DCLK is output, but it cannot be located at the pin of dedicated configure pin.

Can anybody tell me what should I do, just leave them floating?

Thank you.

Derek