I'm installing Catalyst and I receive this error.
AMD kernel module generator version 2.1
Error:
kernel includes at /usr/src/linux/include do not match current kernel.
they are versioned as "3.14.13"
instead of "3.10.17".
you might need to adjust your symlinks:
- /usr/include
- /usr/src/linux
ERROR: I didn't make module
[Error] Generate Package - error generating package : Slackware/Slackware

Never really messed with symlinks and it always confused me. Sure it's an easy fix.

Could you post output of

bash-4.3$ ls /var/log/packages/kernel-*
/var/log/packages/kernel-firmware-20131008git-noarch-1
/var/log/packages/kernel-firmware-20140710git-noarch-1
/var/log/packages/kernel-generic-3.10.17-x86_64-3
/var/log/packages/kernel-headers-3.14.13-x86-1
/var/log/packages/kernel-huge-3.10.17-x86_64-3
/var/log/packages/kernel-huge-3.14.13-x86_64-1
/var/log/packages/kernel-modules-3.10.17-x86_64-3
/var/log/packages/kernel-modules-3.14.13-x86_64-1
/var/log/packages/kernel-source-3.14.13-noarch-1

I don't know if upgradepkg upgrades kernel packages as I used to compile and install kernels from kernel.org

What I think is you run kernel 3.10.17 while /usr/src/linux points to linux-3.14.13

But normally modules installers use include files from /lib/modules/`uname -r`/source/include

Could you post output of:
edit, and to make sure, output of

bash-4.3$ ls -al /usr/src
total 12
drwxr-xr-x 3 root root 4096 Jul 31 15:23 .
drwxr-xr-x 17 root root 4096 Sep 24 2013 ..
lrwxrwxrwx 1 root root 13 Jul 31 15:23 linux -> linux-3.14.13
drwxr-xr-x 24 root root 4096 Jul 23 13:34 linux-3.14.13
bash-4.3$ uname -r
3.10.17

I just thought, maybe it's because I booted into the old kernel entry in my lilo.conf
that has 3.10.17

Yep, you could try another lilo entry for kernel 3.14.13 in lilo.conf, run lilo and reboot then select that new entry

Did that, tried again and this came up:

AMD kernel module generator version 2.1
doing Makefile based build for kernel 2.6.x and higher
rm -rf *.c *.h *.o *.ko *.a .??* *.symvers
make -C /lib/modules/3.14.13/build SUBDIRS=/home/pino/Downloads/fglrx-14.20/fglrx-install.n6IDxa/common/lib/modules/fglrx/build_mod/2.6.x modules
make[1]: Entering directory `/usr/src/linux-3.14.13'
CC [M] /home/pino/Downloads/fglrx-14.20/fglrx-install.n6IDxa/common/lib/modules/fglrx/build_mod/2.6.x/firegl_public.o
/home/pino/Downloads/fglrx-14.20/fglrx-install.n6IDxa/common/lib/modules/fglrx/build_mod/2.6.x/firegl_public.c: In function 'KCL_GetEffectiveUid':
/home/pino/Downloads/fglrx-14.20/fglrx-install.n6IDxa/common/lib/modules/fglrx/build_mod/2.6.x/firegl_public.c:1787:5: error: incompatible types when returni$
return current_euid();
^
/home/pino/Downloads/fglrx-14.20/fglrx-install.n6IDxa/common/lib/modules/fglrx/build_mod/2.6.x/firegl_public.c:1793:1: warning: control reaches end of non-vo$
}
^
make[2]: *** [/home/pino/Downloads/fglrx-14.20/fglrx-install.n6IDxa/common/lib/modules/fglrx/build_mod/2.6.x/firegl_public.o] Error 1
make[1]: *** [_module_/home/pino/Downloads/fglrx-14.20/fglrx-install.n6IDxa/common/lib/modules/fglrx/build_mod/2.6.x] Error 2
make[1]: Leaving directory `/usr/src/linux-3.14.13'
make: *** [kmod_build] Error 2
build failed with return value 2
ERROR: I didn't make module
[Error] Generate Package - error generating package : Slackware/Slackware

I'm at a loss as to what to do from here.

I don't know, I see...
Isn't a module version for kernel 2.6x ?

edit, after quick googlin' see:
https://bbs.archlinux.org/viewtopic.php?id=179894

Ok, but how would I fix it? I don't have a /lib/modules/fglrx directory.

The code to change is in this file:
/home/pino/Downloads/fglrx-14.20/fglrx-install.n6IDxa/common/lib/modules/fglrx/build_mod/2.6.x/firegl_public.c

This is all that exists in the fglrx directory in my downloads.

bash-4.3$ ls /home/pino/Downloads/fglrx*
amd-driver-installer-14.20-x86.x86_64.run check.sh doc

One ongoing issue with AMD drivers I should warn you about is the problem of Proprietary drivers and kernel updates.

Because -current is always in a state of change that could come at any time, especially the kernel, it's often best to stick to using the default X11/Mesa driver, and only use the proprietary drivers on the stable version-numbered releases, that is unless you keep a copy of the installer on hand and update the drivers when a new kernel is released.

Be warned though, not all up-to-date kernels are often supported by Proprietary drivers right away, so you're always taking a gamble.