I must stop replying to my own messages!!
Sorry to waste everyone's time - maybe this will help others switching from OpenFTS 0.2 when Postgres is already compiled.
Having referred back to the Postgres installation instructions I realised that the new version of OpenFTS requires tsearch to be compiled. The reason that the file tsearch.sql was not where is should be in the instructions is because I had not compiled and installed the tsearch source.
Once I had sorted this OpenFTS installed without problem.
One thing to note with the instructions is that the bit that tells you where to
make install should I think say: /usr/local/
src/postgresql-7.2.3/contrib/pgsql_contrib_openfts$ make install
Regards
Richard