Since you are using SQL 2005, once way (where you would have more control over the import) is to use write a CLR stored procedure, that will read the file using a StreamReader that loops through the file and treats each 3 lines (and multiples thereof) as a single record and inserts into the table.
If you go this way, remember you can use
Context Connection = True to refer to the database that you are calling to CLR SP from...
Hope this helps
-Shiva
mycodetrip.com