If you enable encapsulation on a given Ethernet interface, you can create sub interfaces and assign a VLAN ID.
I find it much easier in the CLI. Not sure if it even possible from the Web GUI.
This example uses Ethernet 0/1, but it should apply to the gigabit module ports as well. I haven't actually programmed a 4430, but I know this is how VLANs are done on ethernet ports in the NetVanta. I've done it with the 3430 models. I hope this is what you are looking for.
interface Ethernet 0/1
interface Ethernet 0/1.5
ip address 192.168.5.1 255.255.255.0
interface Ethernet 0/1.1
vlan-id 1 native
ip address 192.168.1.1 255.255.255.0
Worked great. Thanks