How do I run Safari with a proxy on start up by command line?

Hello,

I am using a piece of software called Sahi to perform automated testing of websites. It uses a local proxy to accomplish this task, so it runs the browser with parameters needed so that that instance of the browser is running with the proxy settings. For some reason it's not correctly setup by default with Safari on the Mac. But it has a configuration file where you can set the command line parameters that it runs the browser with.

So when I use Sahi in its default configuration, it doesn't work because the proxy is not configured, and I get an error ( http://sahi.co.in/forums/discussion/4607/sahi-doesn039t-work-with-safari-5-0-1-o n-macosx )

So I need to set the proxy. When I set the 127.0.0.1:9999 proxy in the System Preferences it works. My question is how do I run Safari so that it provides the proxy settings as a command line option?

This way I can add the command line option to the Sahi configuration file so that it runs Safari properly. I don't want to have the proxy settings system wide because I need other programs to work. I don't want to have the proxy settings set for Safari permanently because I also need to be able to run Safari normally outside of this special context.

Any assistance would be appreciated.