My question is: is there a way to force my LimeWire servent as an Ultrapeer?

I am trying to do some measurement which requires that I run my Gnutella servent as an Ultrapeer. Probably because I didn't run LimeWire long enough, I was always a Leaf, although I didn't disable Ultrapeer capability and my connection and OS should qualify my servent as an Ultrapeer.

I understand that there are lots of considerations in deciding whether a node should be an Ultrapeer. But, is there a way to force my LimeWire to be an Ultrapeer? Reading through the code, I found that UltrapeerSettings.FORCE_ULTRAPEER_MODE looks like a property for that purpose. But setting it in limewire.props does not seem to have any effect.

Thanks.