I was having this same issue. I found the driver available through the Slackware package repository. (I figured that since Backtrack was Slackware based, a TGZ file would allow for the simplest install). Since I am not allowed to post links yet, I will just give you the basic address and you can search for "intel" to find the driver. (packages.slackware.it).
NOTE: Installing this broke the X window system for me. I am trying to figure out how and why this happened. Once I fix it, I will keep you posted. If you're feeling adventurous try it and let me know how it worked for you.