There are many discussions on these forums about dyeing WSF
1) Prepare the parts by lightly sanding any imperfections (or use a metal bristled brush) if necessary.
2) Wash the parts in hot slightly soapy water to clean off any dirt or grease. You can leave them soaking for several minutes if you want.
3) Clean the parts (including insides) with warm fresh water to remove all traces of soap.
4) Prepare the dye bath. I use Rit dye with added distilled (white) vinegar to make an acid solution. The concentration of dye depends on how many pieces (and so the surface area) you are dyeing and your final colour requirements e.e deep black or pastel shades.
5) Add the parts and bring the solution to as close to boiling as you can (if it boils it can bubble over and create a LOT of mess). Make sure that all parts are fully submerged and moved around so as to ensure an even dye coating. The dyeing time depends on your colour requirements, but for a nice deep black I use 20-30 mins.
6) Remove and clean off the parts using warm fresh water, leave to dry et voila!
I can't help with your Jacquard IdyePoly question, but it is mentioned in the link above.