No, I do not believe that it is possible. Office 64 bit can not be installed with Office 32 bit. If I might ask, however, why do you need 32 bit Word but 64 bit Excel?

A possible solution, however, is to install 32 bit Word or 64 bit Excel into a virtual machine (http://www.microsoft.com/windows/virtual-pc/) and then just use the other one on your main computer. For example, install 64 bit Office onto your main desktop and then install 32 bit Office onto your virtual machine (Windows XP might make a good virtual machine).