Does anybody know how to create the Hoedown by ELP intro siren

[SteviePBaker]

I've just bought Sub 37 after retiring so as a "normal" keyboard player. I've always wanted too own a Moog so I got one !
Bit I.m struggling a lot to understand properly how it works - has any got any ideas or suggestions or know how to create the brilliant synth intro on Hoedown ?Thanks hopefully in advance !
Steve