I have been trying to follow the instructions given here, but repeatedly get an error message pop-up titled "Mount" stating Access is Denied.
Does anyone have a solution please?
According to the LecoS install page, you need to install python-scipy, python-numpy, python-imaging which you're supposed to be able to install via the OSGEO4W Installer (which is python-PIL, don't looking for python-imaging).
I ran into some errors with the installer, so it didn't actually work when I tried, but I haven't had time to go back and figure out what I'm doing wrong.
I wrote a little quick-and-dirty tutorial to assist you. This is how i installed LecoS on Windows XP for QGIS 1.8.
Download the file here.
I can not help you for MacOS systems. Scipy should be available here as well, but i do not own a Mac for testing.