CREATE EXTENSION without superuser access

I have an app that would benefit from being able to use pg_partman rather than doing it's own ad-hoc partition
management.

Unfortunately, some of the places where the app needs to run don't have root access to the database server filesystem,
soI can't install the extension in the postgresql extensions directory. 

I could get all the pg_partman functionality by modifying the extension SQL script to remove the extension
functionalityand installing the functions in it manually, but then I can't take advantage of the extension features for
backups,config tables, upgrades and so on - and it's probably not going to interact well if someone does a "create
extensionpg_partman" in the database. 

Is there any way to install an extension either from a SQL connection or from a user-defined directory instead of
.../extensions?

(And if not, is there a TODO here?)

Cheers,
  Steve