You will need to have a front and rear sling mount, one for the rail and one for the buffer, unless you can attach it to the stock? Also different slings have different attachments.
Magpul or any other will do just make sure you get the right stuff.
The comps I shoot do not allow sling use, so although I have a rear sling mount on my buffer tube its more for style than substance

Front
http://www.youtube.com/watch?v=IQ5mvFVUrIg