Video tab:
Base res: (your monitors resolution)
Output res: 426x240
Downscale filter: Lanczos
FPS: 30 (or 25)
Output Tab:
Encoder x264
Rate Control: CBR
Bitrate: 400
Keyframe Int: 2
CPU Preset: Veryfast (you can probably get away with setting this to fast or even more since its a 240p stream. This depends what cpu you have though)
Profile: main
Stream is gonna look pretty bad since its 240p but you know you gotta do what you gotta do.