Magento modify/add columns to model resource

I have a module whose flat table I may need to add columns to and remove columns from. I know this can be done in setup, but I have to import data into the table nightly from a web service. The web service may occasionally change their column names.

First of all, does anyone know how to alter table structure in Magento without using raw SQL? Second, does anyone know the best way to do this?

I haven't yet mastered the EAV data pattern used in Magento but would someday like to learn. Any help appreciated.

I had the same thought (or similar) a while ago.
ALTER TABLE in Magento setup script without using SQL

Ivan's answer was particularly good and I still refer to it often. It is essential reading.