I was in the same position as you when I bought my NSX. I knew the basics of driving a stick, but the NSX was the first car I owned with a manual. If you know the basics, you'll pick it up quickly with the NSX. I absolutely disagree with the notion that you should go out and buy another car just to learn stick on (although a professional driving lesson and/or the use of a rental car wouldn't hurt).
The biggest problem I've observed with the way others teach how to use a stick is, they teach it like a step-by-step procedure instead of giving you an idea of what you're really trying to accomplish. For example, when moving from a stop, and the car dies the first half dozen times, they tell you to let the clutch out slower - NOT helpful. What they should explain, before you do it, is how the clutch has a "sweet spot", a narrow range in which it works progressively, that until you reach that range when lifting up the pedal, it doesn't work, but within that range, you can "play with it", letting it out slowly to get a feel for how it engages progressively. Similarly, when upshifting or downshifting, they tell you when to shift, and the car jerks into the next gear - again, NOT helpful. What they should explain is the concept of matching revs, how a given speed matches to certain revs in one gear, and how it matches to other revs (typically 30-40 percent higher or lower) in the next gear, and how before letting off the clutch you want to make the revs match what you're expecting the revs to be in the new gear. If you can understand these concepts BEFORE you actually take the NSX out, you'll pick it up very quickly.