Add 'do_clean := NO' to /etc/kernel-pkg.conf.
As far as using ccache, you are able to specify your C compiler on the
command line. From the make-kpkg(1) man page:
You may control
which version of gcc used in kernel compilation by setting the Makefile
variables CC and HOSTCC in the top level kernel Makefile. You can do
this simply by
% MAKEFLAGS="CC=gcc-2.95" make-kpkg ...
(please see the top level kernel Makefile for variables that can be