hi, i had this problem with my yuna side skirt and this is what i learned.
1) you can dye it in normal water.
2) it takes forever to dye it no matter what trick you do.
3) getting it wet will cause the color to go away.
4) BUT if the water is cold enough then you'll be fine/loose less dye.
5) if you touch it to much (from like... sewing it which i'm guessing you aren't doing) your fingers will change color.
Some good news is if you don't like how it turns out then you can wash it and start over. Because of all the problems I would recommend doing this by hand (wear gloves, i forgot. bad choice) and speed up the drying process somehow. The slower it takes to dry the more dye you'll lose. Hair dryers outside on hot days get the job done