Dunno what synth you're using but it sounds like a fairly simple FM patch. If you've got z3ta+ its pretty easy to make. Sounds like the LFO is controlling the modulating signal a little bit, and also modulating a filter cutoff (no resonance). LFO might be modulating the amp level aswell. Should be fairly easy to recreate, try simple waves like sine or triange 1 octave up, gently 'FMing' a square or maybe even another sine.
You reckon he's modulating the lfo speed (what it sounds like) or he's just sampled a whole heap of notes with different lfo speeds and sequenced the audio? I'm sure either way would work, the latter is maybe easier?