I think the documentation covers this somewgat, but on the CSS devices I've worked with the management port is totally separate from the others. It has to be in a separate subnet, and if I recall correctly, traffic isn't routed out of this interface so it can only be accessed from devices on the local subnet.
This being said, I don't understand the purpose for this port. You can TELNET/SSH to the device via any VLAN interface and collect SNMP as well, so the benefit of utilizing the management port is unclear to me.