Help: make release, just for sysinst changes

[To tech-install and tech-misc...]

I'd like to `make release` but at the moment I'm only working on
sysinst, and `make release` takes forever!  I don't want to bootstrap a
toolchain, nor build dist sets or anything.  I've looked at simply
saying "no" to MK...xxx (nearly all), and setting MACHINE and
MACHINE_TYPE, hoping that only an i386 install will be made (just i386
custom kernel, sysinst and friends, barest essentials for testing a new
CD image with changes to sysinst.)  Also I've not put the usr ...
usr.bin etc dirs there, but build.sh didn't like all my omissions...

Can anyone help me with this?  I want to use the currently installed
toolchain (TOOLCHAIN_MISSING=YES)?? and build just my custom i386
kernel, with my new sysinst so I can test it grabbing dist sets over my
DSL connection.

Also, I am confused at the message "build.sh must be run from the top
level source directory."  (I thought I was in the top level.  I unpacked
src.tgz and syssrc.tgz to /usr/src, and cd'd into /usr/src.)

Thanks very much, I'm not getting anywhere here!

James