You're going to have to make your own trim if you want it to look perfect since it doesn't exist anywhere (unless you want to buy custom lace, but that's really expensive). You're going to want to draw up a pattern for the "triangle" part of the lace and cut it out of either a fabric that doesn't fray, use fray block, or go over the edges several times with a sewing machine (before you cut it out). For the scallop detailing, using a crescent stitch yields good results but keep in mind it takes up a ton of thread (which is pretty much an entire spool). The inner most parts can be done by criss-crossing ribbons.
This is basically what I did for my Aerith dress. The finished result can be found here