the effect is very similar, in keyboard editing tremolo is modulation of volume while vibrato of frequency. There are 8 different preset tremolos in the sound DSP which you can add to a voice, and you can program full control over depth, speed, waveform, reverb mix etc etc.

So add DSP, hold the button, scroll to Tremolo, choose a preset, Edit if wanted, Write to Effect Memory position, then use that Effect Memory with the sound.