rr-workbench is a collection of helpers designed to make working with rr and firefox easier. The helpers expect a work environment set up something like

$HOME/rr
  rr         (clone of rr sources)
  workbench  (clone of this repo)

You'll want to use the workbench directory as scratch space. It knows how to ignore and clean up the trace_* directories created by rr.

Documentation for all helpers is available from

make help

However, the three most useful targets which aren't going to change, are

make clean
  Remove all trace directories.
make [TEST_PATH=dir] record-mochitests
  Record firefox running the mochitest suite, optionally
  just the TEST_PATH tests.
make [FF_URL=url] update-firefox
  Blow away the current firefox build and testsuite and
  download the latest from FF_URL (defaulting to nightly
  builds of trunk).