As of Linux Kernel 2.6.24, you no longer need to patch the kernel to get your Microsoft Ergonomic keyboard to work. With kernel 2.6.30+ and possibly lower, the options that you need to enable to get the keyboard to work has changed. The old settings that needed to be enabled were:
Device Drivers --->
Input Device Support --->
<M> Event Interface
USB Support --->
<M> USB Human Interface Device (full HID) support
[*] HID input layer support
[*] HID simple driver interface
<M> Microsoft Natural Ergonomic Keyboard 4000 Driver
The event Interface has remained consistant. However, the USB section has changed over the different kernel releases:
Device Drivers --->
[*] HID Defices --->
{*} Generic HID support
<*> USB Human Interface Device (full HID) support
Special HID drivers --->
<*> Microsoft
If you choose to go the module way, then the module's name will be: hid-microsoft