In short, not easily.
The only way I know to execute in game macro's via script is to place the macro on a hotbar that can be accessed via hotkey. For example, load the macro into the = slot of your primary hotbar.
Then from scripts you can use:
press =
This will simulate this button being pressed.
However....
Why? Why not add whatever the macro does into you script, class file, etc? What is the in-game macro doing that your script can't do?