I'm running an original floppy install manually in DOSbox, but the settings should be comparable:
Set the scaler to normal3x (so just nearest-neighbour, no fancy edge handling which would give the game a watercolour look), with aspect-preserving scaling. The aspect setting is important, since the game runs at a resolution of 320x200 (16:10) squeezed on a 4:3 screen, and you need to have the emulator correct for that.
Try setting the full-screen resolution to "original", or some 4:3 resolution if that doesn't work. Make sure you use OpenGL output or anything that's not "surface".
I guess the scaler/aspect combination pulls the game up to an 800x600 resolution, which most monitors should be able to handle more or less correctly. You may need to fiddle with your monitor or graphics driver settings so it uses aspect-preserving scaling instead of just filling the (wide)screen.
That should result in a pretty faithful reproduction of the original feeling (read: HUGE pixels), the only thing that's missing is an old-fashioned CRT.
(edit) Attached a "screenshot". Try to ignore the banding, it's an artifact of the camera sensor fighting with the LCD.
Post edited June 17, 2011 by sdancer