PHP 5.0.5 CLI: Am I able to set the Oracle home directory at runtime?

[jtp51]

I have two versions of Oracle installed on a SUN Solaris server:

[FONT=Courier New]/opt/app/oracle/product/8.1.7
/opt/app/oracle/product/9.2.0[/FONT]

Am I able to set the Oracle home directory at runtime using PHP CLI?

Thanks,