with a little effort it should be possible to write your own MACD. The movavg function supports an exponential type as option. Together with the definition of the MACD it should be possible to build your own function, which accepts 3 input arguments to calculate the MACD like you wish.
For testing purposes i suggest, that you compare the results of your function (using the standard values) with the result of the built in MACD. Then you can be sure to made it correct.
If you have access to Financial Toolbox on R2018a or higher, then you can use this function from FEX to calculate the MACD like you wish.