Is it possible to use the Support Renderscript Library with Gradle? If so, how do you include it in your project?
Gradle for Android has now Renderscript v8 support with only 2 lines in your build script. See answer by Austyn Mahoney. Keeping the original answer for historical purpose.
Old Answer:
Gradle supports native RS compilation, but not the RS support library. The reason is that the RS support library is hugely complicated compared to any other support library. The RS support library is actually a Java support library, a set of native libraries backing that Java lib, additional native libraries for every script you compile, and an alternate toolchain for generating both the standard LLVM bitcode and the native libraries for your scripts. Right now, only ADT and Ant support that; Gradle isn't there yet.
However, it's possible to use some parts of the RS support library from Gradle already. If you want to use the RS intrinsics, you can link the Java part of the support library (sdk/build-tools/android-4.3/lib/renderscript/renderscript-v8.jar) and the native components (sdk/build-tools/android-4.3/lib/renderscript/packaged/< arch >/*.so), and then you'll be set.
I know Gradle support for the support library is coming at some point in the not too distant future, but I don't have a firm ETA that I can share.