Never tried this as i don't really need a VNAV Path, but if you're on an intercept course and you extend the centerline. I guess you could just click LNAV, then it will draw a line to the extended centerline and probably give you an accurate path then go back to HDG.
Again i've never actually done this for real.
That works, I've done it before. VNAV gives a real VTRK with LNAV and an intercept. It's not correct in HDG SEL if you're not on an LNAV direct course to the FAF or some fix along the way. In HDG SEL, it shows higher than LNAV until you get on the FAC.