Download from this site
The easiest way to install the Wisext tools is through the SketchUp Extension Warehouse.
You can also install the extension with a .rbz file.
|Windows or Mac|
Installation as SketchUp extension (.rbz):
The extension has got the Extension Digital Signature to be loaded at the highest security mode in SketchUp (see: Extensions Loading Policy)
To uninstall the Wisext plugins, see: Uninstalling