This is the final step and involves running the shockcord and tying on the attachment cord.
Approximate time: 1 hour
Start at the cordlock end of each channel. Tie a figure eight stopper in the shock cord and push it through the shockcord channel. You should be able to just push it through, but can use the knot to help pull it if it gets stuck (usually happens when it hits the seam). When you get it all the way through, tie it off to the Grosgrain loop at the opposite end. Tying shockcord can be tricky. I've found it best to tie a bowline and finish it with a half hitch. Pull everything very tight to be sure the knots are set. Leave the bowline fairly open so that the shockcord can move easily on the Grosgrain. Melt the end of the cord.
Move back to the cordlock end. Cut the shockcord so that you have about a foot sticking out. Run it through the cordlock and tie an overhand loop, then melt the end. I like to slide the cordlocks back down to the seam to help keep them apart.
Do the same for all four shockcords.
The last step is to tie on the attachment shockcord. Use a six foot section for each end. Tie it to each corner with a finished bowline and leave it so it can move. Melt the ends. If you're using a Hennessy hammock, tie two small overhand loops about six inches up on the foot end. You'll clip these together over the hammock in "cold mode". Using them instead of the Grosgrain loops keeps everything snug, but give that extra bit of slack to aid in getting in and out of the hammock.
Attach a cord lock to each loop and you're done.
Congratulations, you've made your very own underquilt. You kick ass!