A lot of the scratchy effects are made by running oscillators (like a pulse wav) at low frequency through a high-pass filter. Usually applying a bit of pitch modulation to the oscillator. You can also vary the width of the pitch to give it some depth.
There's also quite a bit of granular synthesis going on and retriggering of samples. I've heard quite a bit of FM synthesis too. This is something I'm experimenting with more and more.
The voice type effects are often made with patches like you get on the Nord modular. But really the important part of the sound comes from how you apply your filters. Try running a simple oscillator's output through multiple notch filters that modulate over time for instance
strigg is right in that the parameter changes that take place are usually synchronised to the tempo.
Try to come up with effects that you can replicate at will.... Timing is crucial in the newer psy trance. You need to know where to create suspended moments to let the track breathe, and to bounce sounds off against each other, rather than trying to layer them on top of each other and creating a mess.
Bass is all important in Psy though. Try a little bit of variation on your release time to create a bit of groove.
This also depends on what kind of psy you're listening to.... some of the older stuff simply used a lot of variation of the cutoff with high resonance to make those squelchy sounds. I feel its better to keep it minimal, just little dabs of those higher frequency sounds, otherwise it gets too 303-acidy and too dense.
I can go on and on about psy, but I'll stop for now