# before doing anything:

export GO15VENDOREXPERIMENT=1

Running:

mkdir ~/buildbot
cp master/master.go ~/buildbot/
cd ~/builbot
go build -o master master.go
./master -verbose -builderopts -verbose=true

Hacking:

mkdir ~/buildbot
cp master/master.go ~/buildbot/
cp builder/builder.go ~/buildbot/
cd ~/builbot
go build -o master master.go
#hack on builder.go
./master -verbose -buildersrc ./builder.go -builderopts -verbose=true,-skipgo1build=true,-faketests=true

Or, if you want the bot(s) to pull from a local repo (so you can trigger some test commits), here is a setup example script:
https://github.com/mpl/misc/blob/master/camlistore.org/misc/buildbot/prepbot