The following seems to work well if booked/plated through AA.

I have found that by booking flights that you have no intention of flying and later changing the booking to flights on your actual required dates gets around the problem nicely. One thing to ensure is that each flight selected for these dummy bookings departs at least 24 hours after the arrival of the previous segment in the booking. This way all appropriate +++ for stopovers should be charged, but it alleviates any issues with turning a booked transit into a stopover with possible determination of a 're-route' and any addition collection perhaps being required.

Once you are ready to change to your actual desired flights, simply call AA to do so.

It may cost slightly more, but if done carefully and not with international UK departures, it worked OK (at least booking via AA).

I did this in February where I wanted a LHONE4 for travel in June '08, April 09 and May 09. Of course, one cannot book April/May flights for the following year in February.

I booked the desired June flights and some 'dummy' ones in November, representing the desired '09 routings, just not dates.

After doing the June segments, I contacted AA and they have re-booked to my desired April/May flights. There was no charge for this.