Well, here's a few ideas...
You can take the tails and run them through the cast-on, in fairly large stitches, and pull up the yarn. Don't cut off the tails, use them to tie on the pom-poms.
You can decrease fairly quickly for a bit, then change over into i-cord for a few rows and then attach the pom-poms.
Just recently I saw a scarf that ended normally in the square way, and then they applied a giant "fringe" of a bunch of different sized pom-poms. That'd be a few too many pom-poms for me, but it was certainly impressive looking!