I am unsure what you mean by simultaneous? Is it that you want all your systems to request and complete provisioining at the same time? SCS will provision them as client requests are captured by SCS.
I would recommend following the instructions in the SCS User Guide included in your SCS 8 download package. The user guide is quite detailed and covers most provisioning situations/scenarios.
You may also want to check out this site:
It should give you a good idea of the best approach to provisioning your systems based on your current envrionment.