I dont know how is work with almost 1 TB, and i dont know if have a better solution, but if you create a clustered index in this tables using ON filegroup clause sendo to another filegroup ?. And after dropped the clustered index. Lets say you dont have a identity column or PK/UQ, create a new identity column, create a CI in this column and after drop the CI and the identity column. If you have a identity better just create CI in another filegroup and dropped in the end. Obviusly after you dropped all Fk´s..etc...

BOL says

Note: Because the leaf level of a clustered index and its data pages are the same by definition, creating a clustered index and using the ON filegroup clause effectively moves a table from the file on which the table was created to the new filegroup. Before creating tables or indexes on specific filegroups, verify which filegroups are available and that they have enough empty space for the index. It is important that the filegroup has at least 1.2 times the space required for the entire table.

I think in a large table this process will be very expensive..

I have one script (design to SQL2k) and sincerely i never used so i dont say its works, but you can see what the script do and test with small tables.

http://education.sqlfarms.com/education/ShowPost.aspx?PostID=59

I dont know its the better way in VLDB´s.