It is easy if you add it by yourself. For some indicators such as RSI, when it was first introduced to market, there is no moving average in it. Moving average was added later.
if you use auto trade, you should code a 'signal', not indicator, in which you may call the RSI function to get the indicator value, get the moving average, or further get the macd value. your trading signal should be more complicated, such as rsi > 80 and then < 80 AND macd < signal, and short term moving average < longer term moving average, ...
do you use regular multichart, or multichart .net, and which broker you will connect?
I am using Multichart 8.0 and I have to amend the script of an indicator to show it's moving average as the source of the indicator must be a intrument.
But I know starting from Multichart 8.8, the source of an indicator can also be an indicator such that you should add a moving average easily in it, no need to update the script.