Playing around a bit, I found a solution for windows:
1) Browse to C:\Program Files (x86)\VideoLAN\VLC and create a new folder called visualizations
2) Download the latest version of ProjectM from here:
http://sourceforge.net/projects/projectm/files/
3) Extract the .tar and find the folder called presets_milkdrop_200 ***You can use a different preset folder depending on the visualizations you want***
4) Copy presets_milkdrop_200 to your visualizations folder
5) In VLC go to advanced preferences > Audio > Visualizations > projectM and set the "projectM preset path" to C:\Program Files (x86)\VideoLAN\VLC\visualizations\presets_milkdrop_200
6) Save your preferences, then activate the visualizations by going to the audio menu > visualizations > and select projectM
VLC will now begin using random visualizations from the preset folder you specified. With some tweaking, you can probably change the scripts to adjust how long each visualization plays for, etc. Enjoy!