Linux:
/sbin/vconfig add eth1 5
/sbin/vconfig add eth1 4
/sbin/ifconfig eth1.4 192.0.0.8 netmask 255.255.255.240 up
/sbin/ifconfig eth1.5 192.0.1.8 netmask 255.255.255.240 up

Catalyst:
conf t
int fa0/0
switchport mode trunk
switchport trunk allowed vlan 4,5,1002-1005