For some people UMD seems to be a must-have. I'm not one of them. And i still don't think you need it or even can get it high enough to make good use of it on this build. It is a bit of a paradox if you need GH to have a better chance to cast GH scrolls.
For GH i have a Planar Gird and a Draconic Necklace, for True Seeing i switch in a yellow Planar Focus and with the high reflex save i never missed being able to cast fireshield which i think is too short-lived cast from a scroll anyway. If i need FoM i switch in Kundarak Delving Boots. Never missed using heal scroll between fights since i have the Fast Healing epic past life feat but if it really was necessary that's what monks have the free 'Healing Ki' feat for (which should fully heal you with a high WIS) or you simply throw in a quick cocoon. So far i never had a single quest where i used up my spellpoint pool and had to drink a potion or use a bauble.
Maybe it's also because i'm not fond of switching lots of items back and forth during a quest and fill my inventory space with scrolls. But to each his own. If i could reach a high enough UMD to cast no-fail Raise scrolls without switching an item then i would probably go for it but so far i do well enough with my Ring of the Ancestors and my Triple Pos GS shuriken and i will probably leave UMD for Completionists with some Artificer Past lifes and a UMD skill tome from the store.
If you really want to go that way though i think you can also take skillpoints from Move Silently if you don't use it that much. And another good thing to boost your UMD is the Epic Martial Past Life feat 'Skill Mastery' which gives you +3 to all skills which you can turn on and off in favor of 'Brace' as you need it. Of course yugo pots and store pots help with UMD too. Keep in Mind that for a bound +6 CHA shard you need 150 arcane crafting skill (which i do not have on my crafter).
I have no idea though why you want to use Cacophonic Verge in epics at all except maybe to break some boxes and even then you will not be centered anymore if you switch it in. Or did i miss any hidden effects on it? My Sorc has one but surely never uses it in epic content.