Can a folder connection in ArcMap Catalog window be added using Python?

No it is not possible to add "Folder Connections" using Arcpy.

Folder Connections are stored in the ArcCatalog.gx file, which is typically located at

 c:\Users\*username*\AppData\Roaming\ESRI\*Desktopverion*\ArcCatalog\ArcCatalog.gx

This is a binary file, so forget about editing it.

The only thing you could possibly do is to create the Folder Connections you want on one PC, copy the ArcCatalog.gx file to a common location, and then have your script replace the local PC copy of ArcCatalog.gx file with the common one.