FreeBSD CURRENT custom ISO install image: howto?

[O. Hartmann]

I'm desperately looking for howto creating my own FreeBSD 
9.0-CURRENT/amd64 custom installation DVD. Google delivers a lot of 
outdated stuff and I wasn't able to find some hints in the handbook, so 
maybe one here can help.

I've already all sources via 'svn' (no CVS) on the local box. The 
intention is to be able to use new bsdinstall instead of sysinstall for 
having GPT partitions.

Please set me CC if responding.

Thanks in advance,
Oliver