yes there's a couple ways you could do it:

1. download someone else's compiled upgraded version. (Haven't seen one for the S3 yet)
2. install the build env on the S3, and compile your own. very slow CPU in S3, will take a long while. (400mhz Atheros AR9330)
3. install a build-env on a machine with lots more CPU (linux box) and cross-compile. Will likely need custom source for Bitmain custom USB driver as well.

Since I have quite a few of the S3's, I'd like to do #3, but I haven't found a build env for it yet.

Details : OpenWRT -- BARRIER BREAKER (Bleeding Edge, r38031)