This prevents installing the filter to /usr/lib64 on 64bit platforms.

diff -urp ptouch-driver-1.2.orig/Makefile.am ptouch-driver-1.2/Makefile.am
--- ptouch-driver-1.2.orig/Makefile.am	2007-07-27 19:51:05.000000000 +0200
+++ ptouch-driver-1.2/Makefile.am	2007-07-27 19:53:58.000000000 +0200
@@ -18,7 +18,7 @@
 ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
 ## USA
 
-execfilterdir			= $(libdir)/cups/filter
+execfilterdir			= $(prefix)/lib/cups/filter
 execfilter_PROGRAMS		= rastertoptch
 rastertoptch_CPPFLAGS		= -D_GNU_SOURCE