I'm successfully using quilt on sparc64 machine (sun ultra 60) for manipulating kernel patches from mm kernel series. The quilt-0.46.ebuild says: KEYWORDS="amd64 ppc ppc64 x86". I think sparc can be added there. I do not see any problems. Everything works fine. Reproducible: Always If you want me to run any additional tests just drop me an email.
~sparc done, closing