Ok, I could set up a port as vlanid > 15, that's fine. But what about setting up more than one vlan on the same port?
Another question, I read in the ADM datasheet that it is possible to control the bandwith on each port: 256k, 512k, 1M, 2M, 5M, 10M, 20M, 50M. Is this possible with the adm6996 module?

I answer myself. I could configure a few vlans on each port.
But I still have doubts with the bandwidth control that the ADM switch says it performs. In the /proc directory I found the files speed and bandwith, but I think they are for the Physic Medium:

#cat /proc/sys/dev/adm6996/port1/speed
100
#cat /proc/sys/dev/adm6996/port1/bandwidth
Full

I think they say 100Mbps Full Duplex
So I'm not controlling the BW yet.