[Pgpool-general] Errors by running "sh install-functions.sh"

[Felix Noel Abelardo Santana]

Hi I am following the tutorial at
http://pgpool.projects.postgresql.org/contrib_docs/simple_sr_setting/index.html
to try out pgpool-II with Streaming Replication/Hot Standby in Postgres 
9. I am using the new tarball linked
from the page, for pgpool-II-3.1.0-alpha1. When I run sh 
install-functions.sh I see the following errors:

root at desktop:/opt/pgpool-II-3.1.0-alpha1# sh install-functions.sh
Makefile:14: /usr/lib/postgresql/8.4/lib/pgxs/src/makefiles/pgxs.mk: No 
such file or directory
make: *** No rule to make target 
`/usr/lib/postgresql/8.4/lib/pgxs/src/makefiles/pgxs.mk'.  Stop.
Makefile:14: /usr/lib/postgresql/8.4/lib/pgxs/src/makefiles/pgxs.mk: No 
such file or directory
make: *** No rule to make target 
`/usr/lib/postgresql/8.4/lib/pgxs/src/makefiles/pgxs.mk'.  Stop.
Error: You must install at least one postgresql-client-<version> package.
Error: You must install at least one postgresql-client-<version> package.

How can I correct this ?
Which file I have to modify to fix this, if I have postgres 9.0 installed ?
Why the error is with postgres 8.4 ?

Greetings Felix Noel