Hi Greg
Fire fighter is a component of GRC Access Controls
If your client does not want to implement GRC to use the Firefighter functionality then you will need to consider how to handle this via a process (such as assign a temporary role and review what the user does)
If you mean the client wants to use FF but do not want to have a separate GRC system and instead install it off Solman you might want to rethink this. Below is a section form the GRC 10.1 Installation Guide advising standalone. Althought Solman is not in the list I suspect it applies as well as you will have a headache for managing Basis Support Stacks/Upgrades/etc/
3.1Preparing to Install SAP Solutions for Governance, Risk, and Compliance (GRC) 10.1
Install SAP solutions for governance, risk, and compliance (GRC) 10.1 on a standalone system as opposed to installing them along with an SAP Business Suite or with any SAP Business Suite components such as ERP, SCM, CRM, OR SRM.
Regards
Colleen