Dumb question maybe, but have you asked any of these women out on a date? That's the objective, isn't it? Why not just do it and let the penis size take care of itself if it gets that far?
I have a feeling that what this thread (and, apparently, a previous one with the same title) is about is the fear of rejection. You want to somehow let word get out that you're hung, then let the women come to you, with the agenda unspoken but understood by both parties. Perhaps this can work -- I don't know what "phase" (*) your female coworkers are in -- but this doesn't seem like a reliable plan for a 35+ guy.
Man up. Ask one of your coworkers out (like any regular guy would) and be nice and charming and relaxed and confident. In no way, shape, or form initiate a conversation about penis size -- only go there if she blatantly goes there without prodding. You're gonna have to work for this. But if you get to the finish line you'll both be much happier for the better foundation.
Kev
(*) Just an observation -- some women, usually college or just-post-college age, go through a phase where they seem to be trying on different men for size.