This should be easy to use. It's for Windows, between WXP and W10.

1) Install one or more versions of Arduino. 1.0.x or 1.6.5 are known to work; some of the 1.5 and early 1.6 versions might not.

2) Download the .bat file and put it somewhere that you can find it.

3) On your PC, open a "command prompt" window, and execute the batch file. Pick a version of the compiler to "install" when prompted.

4) Now you have command-line access to avr-gcc (and etc), avrdude, and if the Arduino install included make (1.0.x, alas), also "make" and a bunch of unix-like tools.