I realize your original post is a few years old, but I may have a solution for you if you are still looking for help:
My company Eccellent Solutions (www.eccellent.com) provides the services listed in your job description. We also perform routine backup and system maintenance as well, with decades of combined experience and several customers already under our support. We charge a monthly subscription fee that can vary depending on the depth of support you are looking for. We offer an advantage over a direct hire due to the fact that as a company, there would be no PTO taken or health insurance and our rates are very competitive compared to the yearly salary of a single WC administrator.
I personally have done a lot of Windchill workflow work, as well as my co-workers. Please let me know when would be a good time to discuss your WC admin needs. You can reach me at email@example.com or call me at 856-219-2114.