The idea will be the following: OSC-1 will generate a wave that will be synchronized with OSC-2, that is, it will just generate harmonics that are present in OSC-2. So even though OSC-2 volume is set to zero, OSC-2 frequency will be the one guiding the pitch of the tone, and OSC-2 Frequency is set to
The filter envelope will have this strong decay shape, and a very short attack time. We will use the same envelope to change the frequency of the first oscillator, OSC-1, using the Filter Envelope in the Poly-Mod section. Adjusting this carefully will reproduce the characteristic sound.
Now to the R3. We want then to set one oscilator to be sync'd with the second. The first oscillator will recieve a frequency shift specified by a similar envelope, shown below:
Notice however that the option to synchronize oscillators is inverted in the R3, that is, OSC-2 can be sync'd with OSC-1, but not the other way around. That's not a problem, we just invert our programming, that is, In the mixer, the volume of OSC-1 will be set to zero, and the envelope will map to the filter as well to the frequency of OSC-2 (not OSC-1).
This is the final result. Let me know if you have suggestions to improve it.