Sure - you can pass any XMLType column to XMLTransform.
Just select it like I've done passing your table and column instead of RWS and X.
If you're loading the values from files and want to strip the namespace in the process, you should be able to
Create an external table to read the XML files
Load the transformed files with a statement like:
insert into target ...
select xmltransform ( xmlcol, '<xslt ... ' )