Applying master pages

Dear scripters

I have very little experience with scrips in InDesign, but i have an issue I hope can be solved. I'm importing xml-data from a database to create dictionaries. As in a typical dictionary each section starts with A, B, C.. (all running text). For each new letter(part) I would like InDesign to change master page. Letter A --> Master A, letter B --> Master B.. Letter Z --> Master Z.  Would this be possible? The "start" letters is mapped in xml and have it's own paragraph style.

Could it be as simple as: if first character in last paragraph on page is "a" apply "Master A" as so forward?

Any ideas?

Thanks

- Kristin