I always save those patches right from the browser, but not as .diff. I just save them as somefile.patch and then place them in the directory of Wine that I want to compile and run patch -p1 < somefile.patch. You should also issue this command after patching is completed ./tools/make_requests. If you ever want to revert changes made by patching just run patch -Rp1 < somefile.patch and compile that Wine.
