get the xpdf-2.02pl1-i486-1 package, it is the most recent update (with swaret), it does not need libXm.so.3.
Code:
$ ldd /usr/X11R6/bin/xpdf
libXm.so.2 => /usr/X11R6/lib/libXm.so.2 (0x40039000)
libXt.so.6 => /usr/X11R6/lib/libXt.so.6 (0x40179000)
libXp.so.6 => /usr/X11R6/lib/libXp.so.6 (0x401cb000)
libXext.so.6 => /usr/X11R6/lib/libXext.so.6 (0x401d3000)
libXpm.so.4 => /usr/X11R6/lib/libXpm.so.4 (0x401e2000)
libt1.so.1 => /usr/lib/libt1.so.1 (0x401f1000)
libfreetype.so.6 => /usr/lib/libfreetype.so.6 (0x40235000)
libSM.so.6 => /usr/X11R6/lib/libSM.so.6 (0x40299000)
libICE.so.6 => /usr/X11R6/lib/libICE.so.6 (0x402a2000)
libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x402b9000)
libstdc++.so.5 => /usr/lib/libstdc++.so.5 (0x40381000)
libm.so.6 => /lib/libm.so.6 (0x40437000)
libgcc_s.so.1 => /usr/lib/libgcc_s.so.1 (0x40459000)
libc.so.6 => /lib/libc.so.6 (0x40461000)
libz.so.1 => /usr/lib/libz.so.1 (0x40590000)
libfontconfig.so.1 => /usr/X11R6/lib/libfontconfig.so.1 (0x4059d000)
libdl.so.2 => /lib/libdl.so.2 (0x405c5000)
/lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
libexpat.so.0 => /usr/lib/libexpat.so.0 (0x405c8000)
But the ln -s thing should works with
# ln -s liblibXm.so.2.0.1 libXm.so.3