Evolution Motorsport (EVOMs) produce a cover to fit with their intake, I would guess it would work with ITG. Its not cheap though at around 80 quid......
EDIT: Just found it on the JKM website - make that £95 + VAT
TBH, I would use the engine cover you have or source a 2nd hand one from ebay, they are quite straight forward to modify. Alternatively ditch the engine cover entirely I think it looks ok without it.
Just another thought, I could measure mine and give you dimensions, then maybe a metal fabricator could knock you one up, I'm sure it will be a lot cheaper than buying a custom one.