disable driver signature check while installing windows 7

Question

is there any possibility where i can disable the default driver signature check while WINDOWS 7 Instalation?.

My problem is that:

i had bought an asus mobo with inbuilt AMD raid card and i want to install windows on that raid array, but windows require driver to be installed to detect that raid as disk. but unfortunately in 64-bit installation of windows it is not bypassing the driver signature check and not allowing me to install driver as well as the windows. i hope it can b done via extracting the installation iso of windows 7 and then changing some values in some files and then again writing it back as bootable media, but not sure which file to edit or from where to start.

Edit

there are some answers which recommend to use a pure windows 7 64bit installation media or to use microsoft WAIK, but there are lot of people having questions about the same amd raid card and says that the driver actually is not signed and that's why it is creating problems. i just want to know a working solution and the reason for this (for knowledge)