Hey mate, have you tried AMP Futures yet? I know they offer MT5 support.
Also, do you mind me asking why you want to trade Futures on MT4 or MT5?
You'll be strictly limited in your trading abilities using Metaquotes platforms to trade Futures. As you know, trading Futures is a lot more in-depth and transparent than retail Forex (which is what MT4 was designed for). In the Futures markets you can see true Volumes, use a DOM etc. which makes trading very straight forward. The Metaquotes platform is very basic for Futures.
I can understand you might want to use MT4 to trade futures because of the idea of using custom indicators available here but you really don't need any fancy indicators to trade Futures!
As a prop trader at work we hardly used charts at all for trading futures let alone technical indicators, we only used a DOM and that's it.
Let us know how you go!
PS: If you're looking to try Futures for free with a real futures platform you can test out X_trader
here.