In general phase modualtion (PM) and frequency modulation (FM) are very similar. If you use a sine wave as modulator the results are the same. FM with a square wave is equal to PM with a triangle.
In fact the 'FM' in Icarus or the DX7 is technical 'phase modualtion'. The term 'FM' is historical-wrong marketing-speech introduced by Yamaha for 'technical phase modulation'. I got no idea why they didn't call the DX7 a PM synth.
Tone2 Nemesis is one of the few synths wich can do 'true FM' (which sounds much better and is more easy to program in my opinion).
There are several ways of doing phase modulation with Icarus. It is very easy:
1) Phase modulation without a second oscillator
Select 'FM Sine' as 'morph mode' and tweak the morph knob
2) Phase modulation where OSC3 modulates OSC1:
Select a dark or sinoid waveform for OSC3. On OSC1 select 'FM<-OSC3' as 'morph mode' and tweak the morph knob. Then tweak the tuning of OSC3.
Best Regards,
Markus
