Below may help taken from CCO. It applies to 5400 as well.dial-tdm-clockTo configure the clock source and priority of the clock source used by the time-division mulitiplexing (TDM) bus on the dial shelf of the Cisco AS5800, use the dial-tdm-clock glo...

I don't know if you can give precedence based on vc id such as dlci number or vpi/vci pair but you can on interface level give precedence to voip traffic through fancy queueing methods such as PQCBWFQ (create access list with udp port range of voice ...