I don't think there is a profile available for building LFS with 2.6.23, what i don't understand is the fact that your MotherBoard doesn't support kernel below 2.6.23 ?
You need a file called .config to be putted in the kernel source tree before compilation, LFS doesn't provide one, but there is this link wish can help you building your kernel
Index
creating your own kernel profile is not an easy job, if you miss something important your system won't boot, you can try to make your profile by typing make menuconfig in the kernel source tree.
i have .config file for 2.6.23.16 used in my box, but i configure it for my system! but if you want i can send it to you to have a look on it.
__________________
Linux is not only an operating system, it's a philosophy.
For Xfce users with Laptop check
this