This procedure is well supported and recommended under the latest FreeBSD releases and is documented in the Building and Installing a Custom Kernel chapter of the FreeBSD Handbook.
All FreeBSD documents are available for download at http://ftp.FreeBSD.org/pub/FreeBSD/doc/
Questions that are not answered by the
documentation may be
sent to <freebsd-questions@FreeBSD.org>.
Send questions about this document to <freebsd-doc@FreeBSD.org>.