Yes you can . Please note that the mcc documentation is wrong for this subject (already informed technical support for this subject).
I am exactly in the same configuration as you . On my Windows 7 64-bits , I have installed both MATLAB 32-bit and MATLAB 64-bit in different folders. Then within your MATLAB 32-bit you just compile as usual , no need to use the -win32 switch. This will create a standalone for Windows 32-bits. Note that you will be also be able to run this standalone under your Windows 64-bits if you have of course the MCR 32-bits installed on your machine.