I'm going to guess that when the OP said "locking nut" that it was meant towards the twist connector on the end of the qucik release valve. The tubing just needs to be pinched so that it can get under that twist lock. Once its under it, it is pretty simple to get going.
I don't think the OP was reffering to the locks that are used around the intake and out take to get a tight seal. If you are concerned about that I would go with clamps verses zip ties. The zip ties or the locks that came with the filter will ceratinly work but if you are going to lose sleep about a leak, then clamps would be the way to go. You can buy clamps in all sizes at Home Depot or Lowes.