Hello all. I made a bunch of sweet patches for an Ozzie tribute a while back and they are playing again in a couple weeks. I cannot for the life of me figure out how to do the portamento effect at the intro of Mr.Crowley. I am looking for some suggestions on how to best replicate the effect. General synthesis tips would be preferred. What do y'all think?

pitch bend or set portamento with delay. Just hit all the white notes down and then up.