Help with regard to VLAN trunking on RB951

Hi,

I would like to have the following setup:


Internet <----> RB951 <---->Application Gateway (1 WAN + 1 LAN)

The application gateway is capable of VLAN, it would be trunking 3 VLANs viz. Mgmt, Voice, Data with VLAN tag of 100, 200 and 300
On RB951 which has 5 Etherports (1 Gateway, 4 LAN), I would like the following configuration:

Ether5 to connect to a cisco STB (VLAN400), but should bridge, and it will get its IP from IPTV network past internet
Ether4 to connect to WAN Port of Application Gateway which would be carrying the Trunk VLAN
Ether2 and Ether3 acting as LAN ports
Ether1 acting as a Trunk Port carrying all the 4 VLANs (VLAN400 [IPTV], VLAN100[Mgmt], VLAN200[Voice] and VLAN300[Data])

Can anyone suggest me what I specifically need to do on RB951 to get this going ?