You’re planning on constructing all these tags de novo? The combinatorial possibilites are daunting. I think the easiest way is to use vectors from commercial sources that already have these tag sequences in them. Unfortunately, there is no uniform source for all these tags (at least, none that I’m aware of). Most suppliers post their vector sequences (including the tags) online somewhere, though not always in formats that are easy to use. GeneDesigner software carries many of these tags as sequences and objects within the program and has provisions for creating new sequence objects. Although this software is “free,” it is intended to be a way to generate oligos that are then ordered from DNA2.0. You are free to design anything you like, but use of the program’s output is restricted, in theory, and its reporting capabilities are limited. Vector-NTI may also have at least some of these tags within the program to help in designing expression vectors. Vector-NTI is available for free to academics from Invitrogen.