Setting Schema file name for Text Database

I'm trying to use the BDE Text Database driver with an external schema
file. I can get it to work in test cases, but not for real-world
examples because of what appear to be three huge restrictions: 1) the
schema has to have the name of the database file embedded in it, 2) the
name of the schema file has to be the same as the name of the database
file and 3) the schema has to be in the same directory as the database

If I get some data on a CD-ROM, there's no way I can put the schema file
in the same directory as the file, and I don't have any way to know in
advance what the file name will be anyhow. Short of copying every file
to the hard drive and renaming it to match the schema file, I don't see
way to use an external schema file.

Not using an external schema file means I have to get into arcane dbi
calls and bit codes for field maps.

So the question is: is there any way to tell the BDE what schema file to
associate with what Delphi dataset?