Setting the Local Value of a Directive

Is there a way to set the local value of a directive for an extension from within php code? For example, I want to set java.class.path from a php file to ensure that the class path I need is available. Also, if this can be done, is this considered good or bad practice? By the way, has anyone had any problems with the Java extension? I have configured the extension and run it successfully on NT, but I am having some problems with the extension on a Solaris Unix box. After setting the java.class.path directive in the ini file and verifying it with phpinfo(), I am seeing it get wiped out later (i.e. reset to no value). This is why I want to try to set it from the php code before invoking the call to Java(). I know I should ask this last bit on another list, but if anyone has any info on it too, I would appreciate it. Thanks, David