Sorted now. I just got the Boss book off e-bay, and reading it, I came across a rotary effect using a CE-5 chorus and a BD-2 blues driver. The sample on the c.d (that came with it) sounds very close to the While my guitar gently weeps Clapton solo.
I hear what you mean about the Phaser as well, that also worked with the blues driver. I'll try it out with me flanger soon as i get a minute.