virtualbox - Bridging eth0 and vboxnet0 and using ISC DHCP server to provide dynamic IPs

I have Lubuntu 12.04 (64bit) with VirtualBox 4.2 installed and the setup below:

1. eth0 adapter connected to LAN (having static IP 192.168.0.1 and it is the default gateway).


2. ISC DHCP server listening on eth0, to configure PCs (in LAN) with dynamic IPs.


3. ppp0 adapter (wirless Mblaze USB modem) to connect to Internet.


4. eth0 has NATed to ppp0, so that all PCs connected to the LAN can have Internet.


5. vboxnet0 host only network (selected for the Virtual Machines).

I would like to have a bridge combining vboxnet0 and eth0 to make it a single network (say br0) and have the DHCP server serve IPs through this new bridge. br0 now should take the static IP of eth0, so that the bridge can be the new gateway.

Please note I neither need Bridged Adapter nor NAT solution in VirtualBox setting UI. I would like to configure all these manually editing all the associated configuration files.

Any help deeply appreciated. Thanks in advance.