This is what I did with mine Buffman, was down earlier so took a pic:
It is put in from above. Annoyingly I forgot to do the other side lol.
Ah cool, this is what I did (I've got lots of spare 5x2!)
Inb4 joist hanger ragebait
Are you putting your electric cabling externally @dlockers ? I've notched my noggins to allow wiring but not really looked into it.