You need to build a kernel tree:

Download the kernel, rds.patch, voladj.patch and the latest hijack patch into somewhere convenient...eg /home/me/empeg/

Untar the stock empeg kernel:
Go to the root of that kernel.
patch -p0 < ../rds.patch
patch -p0 < ../voladj.patch
patch -p1 < ../v266-hijack.patch (or whatever it's called..(!))

After you have done this, hijack.c should be in arch/arm/special