Go to a gnu mirror and get the latest binutils, gcc, and newlib sources.
(replace the version numbers with what you download, for example binutils-2.15
instead of 2.14).

This has been recently tested on Linux with gcc 3.4.0, binutils 2.15 and newlib 1.12.0


cd /
mkdir arm
cd arm
mkdir bin
PATH=/arm/bin:$PATH
ZZZ='--target=arm-thumb-elf --prefix=/arm'

tar xzvf binutils-2.14.tar.gz
cd binutils-2.14
mkdir build
cd build
../configure $ZZZ
make all install
<takes a while>
cd /arm
rm -r /arm/binutils-2.14

tar xzvf gcc-core-3.2.2.tar.gz
tar xzvf newlib-1.11.0.tar.gz

cd gcc-3.2.2
cp -r ../newlib-1.11.0/newlib/ .
cp -r ../newlib-1.11.0/libgloss/ .

rm -r /arm/newlib-1.11.0


edit gcc/Makefile.in and wipe out these definitions

change from:
STMP_FIXINC = @STMP_FIXINC@
to:
STMP_FIXINC =
change from:
USE_COLLECT2 = collect2$(exeext)
to:
USE_COLLECT2 =

cd newlib/libc/sys/arm

rename or move crt0.S, libcfunc.c, and syscalls.c
then touch them to make empty files
touch crt0.S
touch libcfunc.c
touch syscalls.c

cd /arm/gcc-3.2.2
mkdir build
cd build
../configure $ZZZ --with-newlib  (--disable-libmudflap --disable-libssp on gcc 4.1.2)
make all install
<takes a long while>
cd /arm
save copies of crt0.S, libcfunc.c, and syscalls.c
from /arm/gcc-3.2.2/newlib/libc/sys/arm/
rm -r /arm/gcc-3.2.2

And now you have a compiler/assembler/linker