I am going to be trying to dye my UGJ nozzels with Rit soon and have been reading up on past posts. I don't think you could keep them wet long enough to get the dye penetration and therefore the get color you want. Thats why you need to soak it in the dye solution.
On the otherhand, there have been issues with PVC disforming when heated solution on a stove is used. Regular sched 40 PVC is not for hot water pipes, thats why there is CPVC.
I plan on soaking in WARM and stronger dye mix for a longer time than listed for fabrics, the Rit dye can also be used to dye fabrics in a washing machine instead of simmering in a pot, so it should eventually dye the PVC at lower temps.
Of course I haven't actually done it yet, this is my plan. I keep looking for black, all I have is some navy blue I bought lots of Rit to tye-dye the kids shirts a couple years ago and never used that color.