rendering for placement in composite

[Johnny]

I am designing an image for print which will involve a clear glass sphere positioned in front of a painterly 'swipe'..the sphere has to cast a shadow onto the swipe, refract/reflect the swipe..

IOW, it has to look like it IS there..

my plan of attack is to:

1. do the swipe
2. image map the swipe onto a plane in LW, and position camera, sphere and plane in the relationship I need

3. take that render, select the area containing the sphere, shadow and any caustics into photoshop, and plop it over the right spot in that file.

Am I even approaching this problem correctly?

thanks for any tips!

Johnny