For me it is this -
Lay the fly line & backing side by side
pich the two together between finger & thumb
Take a bobbin holder & suitable thread
Bit fiddly but tie in the thread around the line and the backing just like you would with a fly
Spin the bobbin holder around the line & backing being cafeful that it doesn't smack you in the face or the crown jewels!
At this stage, you should have the backing & line piched togetherin both your left & right hands and the bobbin hanging from them between your hands.
Once you have a fair amout of thread securing the line and backing together, trim off the unwanted ends.
Then cover the trimmed bits with extra thread to create a smooth joint.
Trim the thread neatly having knotted it to prevent unraveling.
Then the important bit.......Superglue!!!!
This is hard to explain in writing but hopefully you'll get the jist. I attach all my braided loops like this aswell. It's far superior to the plastic sleave as it creates a totally smooth link. They come through the rings far better and help reduce tangles.
Bit fiddly but well worth it in my opinion.
Good luck!!