Legacy database migration causing problems during testing

I’m using rails to build some new functionality into an existing
website and MySQL database system. I know there are ways to set up
models to use the legacy tables and that I should be able to get the
application to run properly with the DB in it’s current state. The
problem that I am having is the database isn’t translating into a
schema that can be inserted into the test database. I replaced all the
enum references with varchars, but I’m now running into an error with
the creation of indexes on full text fields.

Mysql::Error: BLOB/TEXT column ‘longteaser’ used in key specification
without a key length: CREATE INDEX ftext ON asarticle (keyword,
title, author, longteaser, articletext, metakeywords)

Is it possible to get the schema.rb creation process to ignore certain
tables and/or characteristics when generating itself? I’ve got about
100 tables, 5 of which I need for the project.

Anywhere you can point me would be appreciated.