setup separate class to work on aiki. over time, folks will integrate aiki into their aikido by themselves or not. trying to do aiki in the traditional aikido class is a losing proposition.
The Ki Society, as other people have noted, does define two areas that need to be developed. The "ki" aspect and the waza aspect. Although there can be a division of, first hour "ki" class, second hour "aikido" class (with variations), both are still taught concurrently. The only problem with this model, is that a student on day one is taught in this manner. I suppose the ideal situation would be to have a new student (or an established student just beginning "ki" training), attend only the "ki" class for a minimum of three months (or longer). After which, the student must
pass the first "ki" rank test, before being brought into waza training. This test contains the bare minimum requirements to show that the student has a good basic grasp on the concepts and early development of the skills.
I think this could be made to work as long as all
of the students have gone through this process and are able to demonstrate the basic skill-set. To Phi's point, this would be putting the responsibility on the student to train every day on the body skills. If they don't put in the work, they won't pass the test(s). The work is tedious, sometimes boring and usually frustrating. This is not thought of as the way to attract new students. However, if the dojo as a whole is able to show a solid grasp of the "ki" skills while showing a good infusion of these skills in their waza, then I think a viable dojo membership takes care of itself. There's just that BIG hump to initially get over.
Of course, all of this hinges on a capable instructor who has gone through a similar process and continues to relentlessly train the basic skills.