I believe what the OP is talking about is the reinker float technique. That technique does require the shimmery white paper.
It is available in the catalog or online
Shimmery White 8-1/2X11 Card Stock - by Stampin' Up!
Now, as for your embossed flowers on whisper white, I would try regular watercolor techniques, pastels, colored pencils like prismas, or you could try a white rose on a colored card base.
If you choose to do something with water...watercolor pencils or crayon or even reinkers with a waterbrush for example...you have to do your brushstrokes with only one or two swipes. The whisper white doesn't like overworking with water.