Where do I purchace an unlock code to build a custom kernel?

[Chris H]

Greetings,
 I've been running a RELENG_* box for some time now. I recently slipped the
same CD into an older AMD k7 box, and performed an install && cvsup.
I then promptly cd /usr/src/sys/amd64/conf && cp GENERIC CUSTOM.
edited CUSTOM to taste, cd /usr/src && make buildworld; wait _hours_.
Then performed:
make buildkernel KERNCONF=CUSTOM
which produced
ERROR: Missing kernel configuration files.

Stop in /usr/src.
*** Error code 1

Stop in /usr/src.

Looks like I got bit by:
20100502:
        The config(8) command has been updated to maintain compatibility
        with config files from 8.0-RELEASE.  You will need a new version
        of config to build kernels (this version can be used from 8.0-RELEASE
        forward).  The buildworld target will generate it, so following
        the instructions in this file for updating will work glitch-free.
        Merely doing a make buildkernel without first doing a make buildworld
        (or kernel-toolchain), or attempting to build a kernel using
        traidtional methods will generate a config version warning, indicating
        you should update.

So I performed: make kernel-toolchain, and tried again. STILL no joy.

So I tried:
To build a kernel
        -----------------
        If you are updating from a prior version of FreeBSD (even one just
        a few days old), you should follow this procedure.  It is the most
        failsafe as it uses a /usr/obj tree with a fresh mini-buildworld,

        make kernel-toolchain
        make -DALWAYS_CHECK_MAKE buildkernel KERNCONF=YOUR_KERNEL_HERE
        make -DALWAYS_CHECK_MAKE installkernel KERNCONF=YOUR_KERNEL_HERE

STILL no joy. Looks like I need to purchase a special kernel unlock key to build
a kernel. :(

Thank you for all your time, and consideration.

--Chris