I am trying to trust the marking for voice traffic in a Cisco 4948E interface/port and it looks like the "qos" command is not working as described in the command reference.
Is there any particular way to configure a port to trust the QoS marking received in a Cisco 4948E - 10GIG switch?
I'm not sure what you find unclear. The QoS behavior has changed and the URL I posted indicates the hardware affected by this change. The 4900 switch is not the same platform/hardware as the 4948E switch.
You need to follow the documentation on the platform in question to configure QoS per your needs.
As I stated before, you need to implement MQC based QoS with policy maps inbound and outbound.
Switchport QoS trust is enabled by default and these isn't any mls qos related commands anymore.
QoS on newer platforms are similar to the behavior you would experience on a regular IOS router.