Can you add the ability to have Xwall compare the X-Originating-IP in Hotmail to SLS lists?

I see you recently added a country lookup for X-Originating-IP and I'm using it. However, I'm getting hammered with Hotmail spam sent from the US and I'd like to block based on the X-Originating-IP. I have to allow Hotmail because of our patrons. Either that or is there a way to use wildcards in header blocking? I tried that but could not find a way to block X-Originating-IP:x.x.x.x without including the full 24 bit address.