That reaction is certainly dependent upon the temperature, so you may get it to epoxidise before it polymerises?
True. It could work.
On the other hand, the Trigonox Application Note says this:
"Without accelerators effective polymerization can be obtained in the 50-200 C Range. For example, Styrene and methyl methacrylate can be polymerized in bulk at 60-100 C"
So, looks like one would have to work below at least 60 C for epoxidation selectivity to prevail. Of course, at low T rates are a different issue.