Does anyone know how to write a mel script that can ideally use a feature from the tool box ( EG. insert edgeloop tool?)
Whenever you make an operation in maya, you'll get a MEL command echo in the script editor.
In this case, for 'insert edgeloop' operation I got something like: polySplitRing -ch on -splitType 1 -weight 0.420764 -smoothingAngle 30 -fixQuads 1 -insertWithEdgeFlow 0 ;
You can then look further into maya's MEL command documentation: https://help.autodesk.com/cloudhelp/2018/ENU/Maya-Tech-Docs/CommandsPython/
and search for polySplitRing
command: it lists all the arguments for this command and some examples.