Bulk hiring of Contingent Workers

Summary

Looking for any lessons learned in bulk onboarding of Contingent Workers (Non employees)

Content

My organisation is looking to bring on 300-500 contingent workers over the next few months.

These will be employees of an outsource provider, but they need to be onboarded and maintained in HCM to provide for system access.

Have any ORC clients experience with this sort of requirement? 

My intended approach will be to engage them individually through a 'quasi-acceptance' to create a Contingent Worker file. Its a lot of individuals to get into processing and I wondered whether there were any lessons learned, or even approaches to managing such a transaction in high volumes?