I might need a little more detail. Unreal Networking is very much the same as it was in UE3 as far as commandline and console arguments. You can still specify <mymap>?listen on the commandline or open <mymap>?listen from the console. Connecting with a client is just 127.0.0.1 or open 127.0.0.1 (localhost for example). Logs are in the \Saved\Logs\ directory structure.
If you are asking about log suppression there is a whole new way to do that. Type log in the console window to get an array of commandline and console options for suppressing/unsuppressing now.
Typically it will be log <logcategory> <fatal/error/warning/display/log/verbose/veryverbose> to change a verbosity level. log <logcategory> with switch between on/off for a given category.
Hope that helps.