if the joystick is attached to the PC and is "seen" by Windows (go to Control->Gamecontroller) then it should just work on Dosbox.
When you start up Dosbox you should see in the console something like "using joystick xyz with .. axes and ... buttons"
When all this is true then you got the first hurdle without having to do anything.
Now you just need to edit dosbox.conf (more on dosbox.conf is in the readme) and in the joystick section ([joystick]) edit it like this:

joysticktype=4axis
timed=true
autofire=false
swap34=false

Additionally there was a patch for WC3's joystick routine that makes the joystick less erratic (the search here could be able to help you find it). if it still does not work correctly, try the "timed" setting (true/false).

Erm nope. Doesn't show any joystick in the box but the Joystick is connected and running properly...

hmmmmm.... no idea then.

Try the alternative Joystick patch for WC III:
http://www.wcnews.com/files.shtml#wc3

Ok now I got the message that the update is running but doesn't get any notebook gameport access. Does this mean that I have to use the crappy old Gameport on my soundcard? I don't even got an adapter?

the patch for WC3 is irrelevant if the 2nd Dosbox window doesn't say a joystick is attached. Why it doesn't find your Joystick is beyond me. My two USB joysticks are found without a problem.

Damn doesn't anybody got a clue?

Plug that same joystick into a different pc and see if it is detected there.

> the patch for WC3 is irrelevant if the 2nd Dosbox window doesn't say a joystick is attached.
In 0.70 it's irrelevant at all. (Use timed=true for WC3 though this will not fix the detection problem)

true h-a-l, I just remembered that I tested this for the first post 0.65 beta, I think.