Hi tore,
You can install a new image using the RS232 port on the Dreambox connected to the RS232 port on your PC using a NULL modem cable and the DreamUp 2.14b program on your PC.
BUT, now the bad news, you cannot add any emus (cams) or k*ys or other addons.
For that you need to use the ethernet port on the Dreambox and the ethernet port on your PC connected by a CROSSOVER ethernet cable. Yes you are right this is a LAN connection but it is the only way to fully use a Dreambox.
You will need internet connection sharing enabled on your PC (so that the Dreambox can share your PC's internet connection via the 56K modem) in order to use internet update directly to the DM7000S. Otherwise you will down load the emus etc to your PC from the internet and use an ftp program to transfer them via the ethernet connection to your Dreambox.
Also keep in mind that it will be best to set up a multiboot system on your 7000 with a standard image in the Dreambox internal flash memory and a number of other (Hydra, Gemini, DBF etc) images installed in a USB memory stick (128MB to 512M
plugged into the DM7000S USB port and using FlashWizard 5.0 as the multiboot manager.
I think you should read some of the beginners tutorials on the stickys on this forum. You will then get the idea of what is involved in owning and making the most of a Dreambox. It may sound a lot when you first read it but taken step by step it's all straightforward, although we all bump into problems now and then.
So, go and read and then post back here, with any questions you have afterwards.
Lots of good people here to help you along if there's anything you don't understand.
73, good luck and happy dreaming.