download gildors umodel.
extract it to somewhere like C:\Umodel\
add that location to your windows path:
go to system properties, advanced, environment variables:
scroll down the varibales list, select "Path", edit, then add ";C:\Umodel\" to the end of the paths list.
now u can use umodel no matter what directory you are in.
(to quick command prompt to a folder, instead of having to type "cd\progra~1\steam\steamapps\common\killingfloor\blahblah" just shift+rightclick on a folder, then select "open command window here", this will open a command prompt in that folder location)