See the Software Prerequisites.

Build executables

Using MSVC6, build "boinc_GUI - Win32 Release" or "boinc_GUI - Win32 Debug" versions as appropriate. This should also build dependent libraries and screen saver.

Build installation package

Open BOINC.ipr. Update the version number:

Readme.txt, license.txt
Resources

Execute "Build Default Media".

Create self-extracting executable

Open BOINC.pfw. Accept all defaults, updating version number.

Anti-virus

Run a virus checker over all the individual (uncompressed) files as well as the final build