Creating an icon for a homebrew installed software (evince) - Mac OS X
Simply use a wrapper like Platypus


Download and install the script wrapper Platypus. 
Create a shell script /usr/local/bin/evince.sh with the content

#!/bin/bash

/usr/local/bin/evince

Open Platypus and create a new app like indicated in the screenshot below:


Choose a nice icon (1024 x 1024 px linked) like this one:

 (48 x 48 px example)

and hit the create button
Save the app to an appropriate folder (e.g. /Applications) and create a Dock item