Spatialite Integration in Cayenne

Hi all,
my issue is related to the recently added support for geospatial types in Cayenne. As I understand it, Mysql and Postgres spatial extensions are already integrated in 4.2M2.
This is great but doesn't fit to my tech stack. My lightweighted application has to use a filebased database (spatialite) and can't rely on a server based solution.
Spatialite is an SQlite extention that adds spatial functionality to SQLite in the same way like Postgis is doing for Postgres.
My current progress is that Cayenne can use connect to a spatialite database via JDBC (using jdbcUrl: jdbc:sqlite:file.db?enable_load_extension=true and SQLSelect.dataRowQuery("SELECT load_extension('mod_spatialite');").select(context);). But all queries fail since the ST-Functions are not implemented yet.

When looking at Cayenne spatial implementation, WKT wrapper were added to the MySQLTreeProcessor and PostgreSQLTreeProcessor.
Both Processors extend a TypeAwareSQLTreeProcessor and and add the "ST_"-Convert commands as required.
In contrast the current SQLiteTreeProcessor extends BaseSQLTreeProcessor. Having no registerColumnProcess, the WKT convert can't take place in the same way like before.
Let me know if someone has an idea how to overcome this problem.
Thanks.