Producing Clutter IQ for arbitrary Waveform

I was looking at https://www.mathworks.com/help/radar/ug/simulating-radar-returns-from-moving-sea-surfaces.html and saw that the radarTransciever() object has a phased.LinearFMWaveform() object attributed to it. Upon looking at this i realize there are only a few types of waveforms available, and it seems NO custom IQ waveform that can be created into a object like phased.LinearFMWaveform() that i can use to define in the radarTransceiver() object and therefore execute the receive(scene).

Ultimately i need to generate IQ off sea surface, with an arbitrary waveform i have predefined/computed.

Is there a way to define a custom waveform that is compatible with what i am trying to do above? or is there another way to generate IQ clutter return with an arbitrary waveform?