Hello,
I wanted a play with zoneminder before I receive my foscam IP-cam, but I had some difficulty getting mjpg-streamer to work with my webcam, or indeed even getting zoneminder to display it; a bit unexpected since it's a UVC webcam (works fine in Cheese etc).
Instead, I used the 'webcam' program (apt-get install webcam) as a quick workaround to capture images at 1 fps.
Documentation for the program can be found in the man page or by googling '~/.webcamrc'
When editing ~/.webcamrc, set local=1 and the program will save images to a local dir instead of uploading them via FTP.
The monitor in zoneminder is set to 'file' and simply points to the local jpg on the disk, which is overwritten every second.
Hope this helps someone who wants to play with zoneminder, but like me is struggling to get their webcam working!
- J