Can I set the proxy on the command line when using org.apache.commons.httpclient?

If an application uses the java.net.* routines, I can set a proxy when invoking the application like this:

java -Dhttp.proxyHost=proxy.server.com -Dhttp.proxyPort=8000 <whatever-the-app-is>

However, I have an application (which I can't change) using org.apache.commons.httpclient to do the http communication. It doesn't specify a procxy server, but it does use the default HttpConnection. Is there some way I can tell the apache http client from the command line to use a proxy server?