Dynamically reconfiguring data rate and PRBS signal with BIST

I am using the altgx megafunction on the Stratix IV GX in BIST mode and I need to dynamically reconfigure the bit rate and PRBS pattern. Is there a way to do so using the altgx_reconfig megafunction? If not, how can I obtain this functionality? I am trying to create a customized test application similar to the Transceiver Signal Integrity Develoment Kit's "SI Demo Application".