SSIS would be my choice for this. A Derived Column Transform after reading the file could append your additional columns before loading the row into a table.

If you want to stay in T-SQL then you can use OPENROWSET and read the entire file as a SINGLE_CLOB and append the columns you want to the resultset:

SELECT BulkColumn AS LineFromFile,

'something' AS Col1,

'something else' AS Col2

FROM OPENROWSET(BULK N'P:\@\1.txt', SINGLE_CLOB) AS Document;

edit: spelling