That should do the trick...
http://documentation.extremenetworks.com/exos_22.1/exos_21_1/netlogin/c_configuring-dynamic-vlans-fo...
# enable the switch to create/delete VLANs d
configure netlogin dynamic-vlan enable
# enable the switch to create/delete the VLAN tagged on the uplink - in this example on port#1
# only needed if you'd like to have the VLAN also on the uplink
configure netlogin dynamic-vlan uplink-ports 1
* X430-48t.62 # sh log12/21/2016 23:55:28.49
Network Login MAC user 14DAE9EC029F logged in MAC 14:DA:E9:EC:02:9F port 33 VLAN(s) "SYS_VLAN_0234", authentication Radius
12/21/2016 23:55:28.26 Port 33 link UP at speed 1 Gbps and full-duplex