I found the tool at C:\U2\UniDK\U2ODBC_64bit\U2ODBC_Tester and things worked well there, although I wasn't able to execute the ".L RELLEVEL" that @Mike Rajkowski mentioned. I was able to execute
CALL Subroutine (*HS.OLEDBINFO) and see all the tables, and also was able to
select * from tables of interest and see data.
Interestingly, when looking at the OLEDBINFO results, TABLE_CAT was blank, TABLE_SCHEM was populated with a value that wasn't showing in SQL Server via the OLE DB for ODBC connection, and all table names where shown with THIS.FORMAT with TABLE_TYPE = TABLE.
When using the "ODBC-Compliant SQL" portion of the U2ODBC Tester (64bit) tool, it's odd that I had to query as
select * from THIS_TABLE to get results (using underscore rather than dot).
I then played around a bit more and got SSMS to throw the error:
"A four-part name was supplied, but the provider does not expose the necessary interfaces to use a catalog or schema."
I was then able to find posts on this in various places on the web, and the solutions offered there worked.
Although I still can't browse columns in the left pane of SSMS on the linked server, I am now able to query it and see columns and data in SSMS.
select * from [LINKEDSERVERVIAOLEDBFORODBC]...[THIS_TABLE];
1. In SQL Server Management Studio, right click on provider named MSDASQL and display properties.
2. Clear the checkbox next to "Level zero only"