Lock users while deploying content

Dear all,

We have a EP 6.0 SP18 installation for ESS/MSS and BW reporting. The user management is taken from an ECC 5.0 backend system. We want to deploy content and apply a series of transports in the portal, and we want to prevent users from connecting to it while this is taking place. We first thought of locking the users, but this will prevent users connecting to the ECC 5.0 backend directly via the sapgui (the ECC 5.0 system is used as a backend for the portal but also as an HR/FI/CO system)

Is there any other way we can prevent our users from connecting to the portal while at the same time keep their access in the backend?

Many thanks

Andreas