Velvia is wonderful to use. The bright rich colors it produces is hard to duplicate with a digital camera. So when I came across this article I was eager to try it out. It is very simple.

Select Image->Adjustments->Channel Mixer.
For Red Channel, choose +120% for Red, -10% for Greeen, -10% Blue (Total 100%)
For Green Channel, choose -10% for Red, +120% Green, -10% for Blue, (Total 100%)
For Blue Channel, choose -10% for Red, -10% Green, +120% for Blue (Total 100%)

Voila!

Note: You can increase the strengths of the adjustments, making sure you total 100% total. See effects below.