How can I have specific crew mix loaded in Primavera?

You can add resources in Primavera (Client or Web) and specify them as labor, nonlabor or materials. Sounds to me that you want to have skilled laborers as resources and that is fine. Probably want to break the resources out by group. Carpenters, welders, plumbing, etc. You can then assign each resource a specific bill rate that will roll up to your respective project.