A key element for outsourcing critical parts of a business process in Service Oriented Architectures are Service Level Agreements (SLAs). They build the key element to move from solely trust-based towards controlled cross-organizational collaboration. While originating from the domain of telecommunications the SLA concept has gained particular attention for Grid computing environments. Significant focus has been given so far to automated negotiation and agreement (also considering legal constraints) of SLAs between parties. However, how a provider that has agreed to a certain SLA is able to map and implement this on its own physical resources or on the ones provided by collaboration partners is not well covered. In this paper we present an approach for a High Performance Computing (HPC) service provider to organize its job submission and scheduling control through long-term SLAs.