How do I set ServicePointManager.DefaultConnectionLimit in the portable framework?

I need to use multiple tasks that will hit a webservice end point. Each task will be streaming data and will have a httpWebRequest connection open.

I need to set the property ServicePointManager.DefaultConnectionLimit to a value greater than 2, but I'm using the portable framework and the ServicePointManager class is not available (should be in System.Net).

How do I allow more open webrequests in the portable framework?

Regards.