spinners,

Have you looked at shoestring shaders' proximity shader? I think you could use that as a mixer so that the shader mixes between your normal shader and a transparent as it gets closer to the box. Here's the URL

http://www.des-web.net/shoestring_graphics.html

Not sure I can help with the keyframe problem.

Good luck,
Eric Winemiller
Digital Carvers Guild
3D plug-ins for Carrara
http://digitalcarversguild.com

Eric Winemiller
Digital Carvers Guild
Carrara and LightWave plug-ins