If you have a UDK source licence, sure. A quick grep through the UDK script source doesn't come up with options to turn self shadows off, just the known options for no shadows at all or self shadow only.. etc.
The shadowing routines aren't exposed to the object shader portion of the engine. At least not the part accessible through the shader editor. I'm not sure there's a script or high level solution to what you're looking to do. IF you absolutely need the day/night cycle then no it probably wont work well. The shadow mesh I…