Is this mysql create table able to be written as a migration?

CREATE TABLE `searches` (
      `id` INT UNSIGNED NOT NULL ,
      `account_id` INT UNSIGNED NOT NULL ,
      `searchable_id` INT UNSIGNED NOT NULL ,
      `searchable_type` VARCHAR(255) NOT NULL ,
      `searchable_text` TEXT NOT NULL ,
      PRIMARY KEY ( `id` ) ,
      FULLTEXT (
      `searchable_text`
    )
    ) ENGINE = MYISAM

Well you can execute arbitrary sql in a migration so yes. You'll have to add the fulltext index by writing a chunk of sql, create_table should be able to handle the rest.

Fred