EPoX went out of business a couple of years back so you cannot approach them, and a quick search of the usual suspects such as MOBOT has not returned anything other than a spec sheet here.
Sorry, looks like you are out of luck unless you can find a fellow owner who still has access to a manual.
Alternatively, what problems are you having that you need the manual to help with? It may be that DaniWeb members can help without the specific manual being required.
I'm wanting to build a new computer but I'm having trouble, it's been a long time since I've built one and my head is starting to spin just looking at ...