Hi Wojo,
Sorry for the core shot info, I hadn't seen the mold you were talking about. Since I mentioned core shot I'll explain it first. A core shot is where you pour a little plastic in the spru of an injection mold, and then inject it. The spru is the part of the mold where the injector goes. To get a good core shot takes some practice. If done correctly it can give an effect similar to the one in the picture you posted.
Now to the 605 mold. I went to Bass Tackle and that appears to be a 2 piece open pour mold. You should be able to just pour your first color in, pour a purple stream where you want in the middle, then top off the mold with you final color. Sounds easy right? Well, it's not. Hand Pouring, especially different colors, is a real art. Your plastic temps have to be pretty spot on, and your timing has to be pretty spot on or you will either get cold cracks (your plastic was to cold), or a swirled mess (your plastic was to hot).
Ultimately this is about viscosity (thickness of your plastic), which is controlled by temperature. Every plastic is a little different, so it would be tough to give you exact temps.
There are a handful of guys who are really good at this, hopefully one has this mold or a similar one and can chime in with better words of wisdom. However, it is ultimately going to be a trial and error process for you with your temps and timing. Make sure you have a good thermometer and take notes so you can reproduce it. You are going to need to keep multiple plastics hot at the same time so you will need a way to do this.
Let us know how you progress.
Jason