The steps to configure on kernel.org are currently unavailable. The official site of Perforce saved a copy. Following normal steps to write .p4config to setup p4client and install p4 and git-p4 into $PATH,
$ git p4 clone //depos/path /local/path
would just work. After local commit of git, $ git p4 rebase && git p4 submit
works just like $ git pull --rebase && git push
to remote git repository.By the way, if you use Mercurial there is also a perforce extension can enable hg to clone perforce repository directly with a few of setup.
However, I strongly recommend perforce users migrating to modern distributed revision control system. After all, all the best companies and organizations have given Git / Mercurial a big hug, such as Github, BitBucket, Apple, Google Code, Perl, Rails, Gnome, Debian, Android and Linux Kernel. The git-p4 is a good transformer.
2012-04-26 update:
The git-p4 is now part of the git distribution and the version on github is no longer updated and doesn't work.