I have written previously on the integration between SuccessFactors an SAP HCM and pointed out a short video that gave a high level introduction to the topic
Further information about the HCM SuccessFactors hybrid integration can be found on the SAP Community Network under hybrid solutions. A hybrid solution combines the best of both worlds: on-premise and cloud. These hybrid scenarios leverages the functions provided by SAP ERP HCM and SuccessFactors Solutions to offer a comprehensive, fully-integrated solution that supports every stage of the process described in the scenario
The following scenarios are covered:
SAP ERP HCM and SuccessFactors Talent Solutions
- Basic Employee Data
- Compensation
- Recruiting
- Workforce Analytics
SAP ERP and SuccessFactors Employee Central
- Cost Center Data
- Employee Data
- Organizational Data
- Payroll
I found a lot of helpful information in this site, particularly the prerequisites,
Hybrid Solutions Link
If you are interested in deploying the hybrid solution quickly please have a took at the Rapid Deployment Solution