I'll take a stab at this question, though I hope MacMillan of Rathdown or one of the other experts chimes in to confirm or correct my answer.

As far as I understand it, the answer is no. The "generally" given in that statement from the pamphlet is to cover extenuating circumstances in which somebody who wasn't a Scottish national was granted arms for an extraordinary reason; I imagine such an event is rare in the extreme.

The only way for someone who is not a Scottish citizen to register arms with the Office of the Lord Lyon is to find an ancestor or living relative who lived/lives in Scotland and who is armigerous. If such a person can't be found, you can petition a grant for your deceased Scottish ancestor and, if you're not the direct heir of those arms, petition a cadet matriculation of those arms (with suitable difference).

That doesn't mean that you don't have any say in the appearance of the arms. From everything I've heard, Lord Lyon is very flexible when it comes to designing arms for new grants to both the living and deceased; though there are strict rules and guidelines that must be followed and the arms should appear similar enough to the chiefly arms as to be easily recognized as belonging to someone of the same name (a good example of this can be found in the panels for the Hunter arms shown on the Caber Dancer website).

I hope I haven't just given you the same lecture that you've come to expect!