I would not suggest glue. Some glue will have elasticity, sure, but will eventually fall off (if not immediately) when the fabric stretches.
For my Amano Rydia tights, what I did was I made applique patches out of the same lycra and did the beading on that, then I hand-sewed the beaded patch onto the fabric. Worked really well and didn't cause any strain on the actual tights.
2014 - Upcoming Conventions :
Anime Weekend Atlanta (GA)
Upcoming costumes : Princess Garnet (coronation gown) from FFIX, Edea Lee (various costmes) from Bravely Default, and more!