Getting the source
The source code can be downloaded as tarballs, e.g. here for OOo2.2.1. In case there are newer releases or for developer snapshots please see the Download Central Development section. The source is huge, so it was split to several files: for newer releases than OOo2.1 substitute OOo_2.1.0_ accordingly:
For a full build you need them all. For development, src_core is usually all you need.
Download them to one directory and unpack them. Information how to checkout from CVS follows.
You might be interested particularly in the Get the source code section in the build guide. It is written for Linux, but it is quite similar for all the platforms.
export 'CVSROOT=:pserver:email@example.com:/cvs' cvs login (CVS password: anoncvs) cvs co -r <milestone> OpenOffice2
There are loads of versions of OO.o, and several choices of branch, with multiple outstanding patch sets. I recommend you build from up-stream CVS HEAD milestones (SRC680 milestones), with patch sets to make them easier to build from 
The very latest ooo-build (a small ~1.5Mb build wrapper) can be got from SVN thus:
svn co http://svn.gnome.org/svn/ooo-build/trunk ooo-build
Note: You are going to need to download an additional ~150Mb of compressed source, and have ~3Gb of space to unpack and build it in.
Checking out a CWS through CVS
This section is a draft!
First, find the CWS name such as picom. Then, lookup the CWS name in EIS (e.g., picom). Notice "Milestone (current)" is m222 (in this example as of time of writing): that is the base milestone. Then, notice the affected modules listed under "Modules & Files."
You will checkout the base milestone from CVS. The convention for base milestone is SRC680_m### (later DEV300_m###?). Then in each affected module (where a module is basically a directory), you will update the module with CVS. The convention for the revision tag for the CWS is cws_src680_####.
Here is a script.
#!/bin/bash # configure these variables according to the particular CWS AFFECTED_MODULES="basebmp basegfx canvas comphelper cppcanvas \ desktop filter goodies offapi offuh psprint sal \ slideshow solenv testshl2 tools unotools vcl xpdf" BASE_MILESTONE_TAG=SRC680_m222 CWS_TAG=cws_src680_picom export CVSROOT=':pserver:firstname.lastname@example.org:/cvs' echo 'Enter the password is anoncvs' cvs login cvs co -r $BASE_MILESTONE_TAG OpenOffice2 for d in $AFFECTED_MODULES do echo "updating module $d" pushd $d cvs up -dP -r $CWS_TAG popd done
If you have a working ~/.cwsrc configuration file setup and the SOLARENV environment variable is set to an already existing solenv directory of a previously checked out OOo tree, e.g.
You also may use cwsquery to obtain the current milestone of the CWS with
When scripting this it is a good idea to check the exit code of cwsquery commands in case your ~/.cwsrc is broken or the environment prerequisites aren't met or the EIS database isn't reachable, so add the following after each cwsquery command:
if [ $? -ne 0 ]; then echo 'cwsquery unsuccessful.' exit 1 fi
If you already have ~/.cwsrc working and a milestone master build ready and want to work on a CWS based on that milestone see Tuning in to a CWS, which offers a method that does not require to rebuild the entire tree.