If you need a boa quickly (with accessories!) the tutorial on how to make a 10 minute boa will be helpful.
Although I never needed a boa quickly up until now ;-))
Originally it is crocheted, but I am sure that you can finger crochet (see Links below) or make a fingerloop braid.
Links:
10 Minute Boa
Concerning finger crochet:
Finger Crochet Jewelry
Crochet a Bracelet With Your Fingers
Here at unikatissima: Fingerloop Braiding