I think the discussion may have gone a bit off track.. If you're looking to do transparent mode firewalling like ScreenOS, then yes, that's only available in SRX 3000 and 5000 series.
I believe, however, that you're just looking to emulate a bgroup, like an SSG. That's actually fairly simple. Syntax is identical to EX switches. A ScreenOS bgroup is roughly equivalent to a JUNOS vlan+rvi (routed vlan interface).
An example that will make a bgroup out of the first 4 ports on an SRX210, and assign IP 192.168.1.1/24:
set int ge-0/0/0.0 family ethernet-switching
set int ge-0/0/1.0 family ethernet-switching
set int fe-0/0/2.0 family ethernet-switching
set int fe-0/0/3.0 family ethernet-switching
set vlans default l3-interface vlan.0
set int vlan.0 family inet addr 192.168.1.1/24
Note that you can't have both family ethernet-switching and family inet configured at the same time on the same interface. At that point, you'll need to assign vlan.0 to a zone, just like it was a physical interface.