You got it.  Loosen the nut, slide the manifold down over the stud and, once everything is good and the "elbow" ends are all snugged down, tighten the nut down.  Just be careful not to tweak the manifold.  I've seen a couple that required a washer or two to shim a slight gap between the manifold and engine case.

If you have to go through the trouble of messing with stud removal, I'd say just let it ride on the stud.  about 10% of the dual ports I've torn down for whatever reason have actually had the manifold affixed to the stud.  It will still be anchored at both ends by the "elbows" and, if you're retaining the original exhaust or an aftermarket set-up with the original style intake heater connections, these will keep the intake from "twisting" from front to back.  You should be fine with this.  I personally ran one dual port that I knew of like that for 4+ years.