I just re-wrote the ET_Pickup plug-in / addon as it wasn't working with reference models. Strange how I find out years later that it doesn't work! Either way, this should work since I changed it from keying the Active Parameter on constraints to the BlendWeight parameter.
Download (Right Click > Save Target As)
This plug-in gives animators an easy constraint workflow for picking up and putting down objects. Most useful for character animation but also works for other instances where one object picks up another.
Download(Drag & Drop into Softimage viewport or right click > "save target as")
Go to the File > Plug-In Manager and right click on the ET_Pickup Add-on and choose 'Help' to view documentation.
This plug-in now works in all version from 6.5 >. Please un-install previous versions and re-install newly downloaded file.