$ sudo emerge -u ati-drivers
Password:
Calculating dependencies... done!

>>> Emerging (1 of 1) x11-drivers/ati-drivers-8.28.8 to /
 * ati-driver-installer-8.28.8.run MD5 ;-) ...                            [ ok ] * ati-driver-installer-8.28.8.run RMD160 ;-) ...                         [ ok ] * ati-driver-installer-8.28.8.run SHA1 ;-) ...                           [ ok ] * ati-driver-installer-8.28.8.run SHA256 ;-) ...                         [ ok ] * ati-driver-installer-8.28.8.run size ;-) ...                           [ ok ] * checking ebuild checksums ;-) ...                                      [ ok ] * checking auxfile checksums ;-) ...                                     [ ok ] * checking miscfile checksums ;-) ...                                    [ ok ] * checking ati-driver-installer-8.28.8.run ;-) ...                       [ ok ] * Determining the location of the kernel source code
 * Found kernel source directory:
 *     /usr/src/linux
 * Found sources for kernel version:
 *     2.6.18-suspend2
 * Checking for MTRR support enabled ...                                  [ ok ] * Checking for AGP support enabled ...                                   [ ok ] * Checking for DRM support disabled ...                                  [ ok ] * X11 implementation is xorg-x11.
>>> Unpacking source...
 * Unpacking Ati drivers ...                                              [ ok ] * Applying ati-powermode.sh.patch ...                                    [ ok ]>>> Source unpacked.
>>> Compiling source in /var/tmp/portage/ati-drivers-8.28.8 ...
 * Building the DRM module...
make: Entering directory `/usr/src/linux-2.6.18-suspend2'
  CC [M]  /var/tmp/portage/ati-drivers-8.28.8/work/common/lib/modules/fglrx/build_mod/firegl_public.o
/var/tmp/portage/ati-drivers-8.28.8/work/common/lib/modules/fglrx/build_mod/firegl_public.c:447: warning: initialization from incompatible pointer type
/var/tmp/portage/ati-drivers-8.28.8/work/common/lib/modules/fglrx/build_mod/firegl_public.c: In function `firegl_stub_open':
/var/tmp/portage/ati-drivers-8.28.8/work/common/lib/modules/fglrx/build_mod/firegl_public.c:570: warning: assignment discards qualifiers from pointer target type
/var/tmp/portage/ati-drivers-8.28.8/work/common/lib/modules/fglrx/build_mod/firegl_public.c: In function `__ke_vm_map':
/var/tmp/portage/ati-drivers-8.28.8/work/common/lib/modules/fglrx/build_mod/firegl_public.c:3175: error: `VM_SHM' undeclared (first use in this function)
/var/tmp/portage/ati-drivers-8.28.8/work/common/lib/modules/fglrx/build_mod/firegl_public.c:3175: error: (Each undeclared identifier is reported only once
/var/tmp/portage/ati-drivers-8.28.8/work/common/lib/modules/fglrx/build_mod/firegl_public.c:3175: error: for each function it appears in.)
make[1]: *** [/var/tmp/portage/ati-drivers-8.28.8/work/common/lib/modules/fglrx/build_mod/firegl_public.o] Error 1
make: *** [_module_/var/tmp/portage/ati-drivers-8.28.8/work/common/lib/modules/fglrx/build_mod] Error 2
make: Leaving directory `/usr/src/linux-2.6.18-suspend2'
 * DRM module not built
>>> Source compiled.
>>> Test phase [not enabled]: x11-drivers/ati-drivers-8.28.8

>>> Install ati-drivers-8.28.8 into /var/tmp/portage/ati-drivers-8.28.8/image/ category x11-drivers
 * Installing fglrx module
install: cannot stat `fglrx.ko': No such file or directory

!!! ERROR: x11-drivers/ati-drivers-8.28.8 failed.
Call stack:
  ebuild.sh, line 1546:   Called dyn_install
  ebuild.sh, line 1020:   Called src_install
  ati-drivers-8.28.8.ebuild, line 204:   Called linux-mod_src_install
  linux-mod.eclass, line 497:   Called die

!!! doins fglrx.ko failed
!!! If you need support, post the topmost build error, and the call stack if relevant.