Create a table with TEXT column type.
generateChangeLog and push to new schema
diffChangeLog on the two.
The only change will be to change the column to CLOB.
There's a second bug (CORE-1592) regarding this that may make this a moot point. But it does seem add that the changeset generated from diffChangeLog does modifyDataType to TEXT or LONGTEXT, but to CLOB.
Linux and MySQL