Well, here it is my version of that strategy.
1. Metatrader does not have 3 min timeframe, so I used 5 min. Periods for channel and big ma converted to get the same results on bigger timeframe: 100 on 3 min = 60 on 5 min and 360 on 3 min = 216 on 5 min. You can change/optimise them.
2. Metatrader does not have Keltner channel indicator but Envelopes looks very similar to description for Keltner channel I could find. So I did not know what width = 300% means. Env_deviation should be similar parameter to change width of channel. You can change/optimise it too.
3. TradeType - 1 is scalping, 2 - swing trade. Expert works with single order only.
4. Move_SL_to_breakeven - move (1) or not (0) stoploss to breakeven as it was recommended or just use the general trailing stop rule.

Look the code and you can find some stuff you can adjust: Mode for Moving Averages (deafaul is simple MA), applied price (default is typical price)

Finally, I could not make this strategy profitable on long history. But the similar one with trading inside the channel looks promising.