Not sure how experienced you are in photoshop- but here are a few tips
1.work in Layers- duplicate your snake layer and work on the duplicate layer.(that way you can always go back to the original.)
2. Use the pen tool and Paths to make you selection.
***Save your paths that way you can always come back to them if you want.
3. under:Image-adjustments-variations play with the color and depth until you get the color you like. When makeing a signifigant color change make sure to change all accordingly: shadows,midtones, and highlights. Click OK
4. go back in to your recolored areas and Dodge and Burn to make it look a little more realistic.
*** Note you can also add color on a separate layer and then play with the Transparency setting too...this is great for creating logo "watermarks" on your photos.
Just got the new CS2 version...it's awsome.
If you want more specific instructions shoot me and email.
Have fun!
A.

-----
"There is a fine line between a hobby and mental illness"