there is opencl.msi in catalyst installer. maybe that will help you? try extract it and use that.
I had a similar question back in July 2011. You can see the message here
I then followed that up with a lengthy offline conversation with AMD the conclusion of which was that end-users had to install the Catalyst driver in order to get the OpenCL runtime. Just using the opencl.msi from the catalyst driver was not a supported mechanism.
I still, like you, think it would be good to have a standalone OpenCL runtime installer. Intel offer one. As applications, we could install this runtime and be certain that at least OpenCL on CPU would work.
That sucks; as the Catalyst won't install if you have a CPU only without an AMD GPU.