Shorewall users - Sep 2013 - DNAT from external to a internal device which doesn't have default gateway

I need to access externally (via Internet) one device in internal network
which has no default gateway configured.
As the device doesn''t have default gateway, the response to SYN (ie,
SYN/ACK) don''t come back to Internet.
What I need is a setup to make this connection appears to come from
firewall''s internal IP address instead of the public IP of originating
requester (SNAT).

I read FAQ 2 (http://www.shorewall.net/FAQ.htm#DNS-DNAT) for a similar
situation.
It''s look like the FAQ is about accessing Internally. My need is to
access
Externally.
In fact, I tried to implement that solution but I got confused and
didn''t
work.

The trivial DNAT rule (which doesn''t work because the lacking of def gw
at
device) is:
  DNAT    net:$SOME_SPECIFIC_EXT_IP    loc:$DEV_NO_GW_SET:80    tcp    8080

The rule at FAQ says
  DNAT       loc          loc:192.168.1.5    tcp      www         -
130.151.100.69
where the source and destination zones are the same (!?).

Do I need to use 2 DNAT rules ?

Another doubt is masq entry.
   eth1 eth1 $FW_INTERNAL_ETH1_IP tcp 80

How can I use different ports for external (8080) and internal (80) for
this setup ?

Thanks everybody !


------------------------------------------------------------------------------
LIMITED TIME SALE - Full Year of Microsoft Training For Just $49.99!
1,500+ hours of tutorials including VisualStudio 2012, Windows 8, SharePoint
2013, SQL 2012, MVC 4, more. BEST VALUE: New Multi-Library Power Pack includes
Mobile, Cloud, Java, and UX Design. Lowest price ever! Ends 9/20/13. 
http://pubads.g.doubleclick.net/gampad/clk?id=58041151&iu=/4140/ostg.clktrk