The same steps are applicable to just about any Indicator.
In MT4
Click on File > Open Data Folder
Open MQL4 > Indicators
Copy the Indicator file into the Indicators folder. You may drag and drop the file or manually do CTRL+C, CTRL+V.
Close the folder and then restart MT4 (close and then reopen MT4).
From the Navigator, expand Indicators and look for the one that you wish to install. Double-click on it or drag-and-drop it into a chart. Click OK.
In MT5
The process is the same. Except in step no. 2, you’d open MQL5 instead of MQL4.