Set include_path for SimpleTest under Eclipse

I am trying to set the include path for SimpleTest under Eclipse

I have the following config :
Eclipse : 3.2.0
PHPEclipse 1.1.8
SimpleTest plugin : 0.2.1

I ran a test I found on the SimpleTest plugin page and it worked fine
http://simpletest.org/en/extension_eclipse.html

I am now trying to test an existing class but when I call :
> require_once('mylog.php');

I get the following error :
----
PHP Fatal error: require_once(): Failed opening required
'mylog.php' (include_path='.:/usr/share/pear:/usr/share/php:/home/
user/.eclipse/org.eclipse.platform.ide/updates/eclipse/plugi ns/
net.sf.simpletest.eclipse_0.2.1/simpletest') in /home/user/workspace/
project/test/simpletest/tests/test_log.php on line 4
----

I would like to find a way to add one or more paths to the
include_path directive (using an eclipse or a simpletest setting).

I would prefer to avoid adding something like that to the code :
ini_set('include_path', $classdir . ':' . ini_get('include_path'));

Any ideas ?

Thanks,
Bastien