the 5600 model doesnt have a lan port. You need to do everything via the serial port which is going to be a real hassle. does the latest hydra support the serial port for coms ?
if you had the 5620 which does have a lan port you would be ok.
I have noticed a few tutes around that mention on how to use the serial port for coms, and there are a few images which support it. try dreambox.net.au
on this page
http://www.dreambox.net.au/dm5600.php there are two images that i can see that may be able to support the com port
dm5600_v101_with_pppd.v1.bin
hydra_5600_ppp_2412.img
the latest Hydra image may support the serial port, im not sure. Good luck.