internal overflow questions

[rusty shackleford]

so im planning to drill a biocube 29 for a sump, already ripped out the back wall.
i have no idea how to go about an internal overflow...
i basically wanna do exactly what this guy did -http://www.youtube.com/watch?v=MiULCECRU10

just wondering if i can just get the actual box and bulkhead or if there is something in there to help quite it down or somthing (baffle/standpipe type thing)

if someone could maybe explain what they think the tank in the video was constructed that would help greatly

thanks all