icecream cflags, cross-compiling (kde4)

[Joseph_sys]

I'm trying to use icecream to test cross-compile kde4
but I'm not very clear how cross-compiling should be correctly setup.

Box-1 (quad core):
CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=nocona -O2 -pipe"

Box-2:
CHOST="i686-pc-linux-gnu"
CFLAGS="-march=athlon-xp -O2 -pipe -fomit-frame-pointer"

emerging icecream I got a note:

* If you have compiled binutils/gcc/glibc with processor-specific flags
* (as normal using Gentoo), there is a greater chance that your compiler
* won't work on other machines. The best would be to build gcc, glibc and
* binutils without those flags and then copy the needed files into your
* tarball for distribution to other machines. This tarball can be created
* by running /usr/bin/icecc --build-native, and used by setting
* ICECC_VERSION in /etc/conf.d/icecream
* ICECC_VERSION=<filename_of_archive_containing_your_environment>

My question:
Do I need to remove from "CFLAGS" all the flags except: -O2 -pipe (since they are common) and re-compile: gcc, glibc, binutils ?

Since one is x86 and one amd64 it seems to me I need to emerge sys-devel/crossdev

Looking at Gentoo doc page: http://dev.gentoo.org/~bluebird/icecream.xml?style=printable
Corss-Compiling section - Code Listing 3.3: Create an icecc environment for cross-compiling
there is a typo: the command in this section and others should be run as root (not as user) I think, is it correct?

What is the correct sequence to run the commands:
1.) /usr/bin/icecc --build-native
it creates I think local environment (before removing CLFAGS and recompiling gcc, glibc, binutils) is it correct?
this command is not mentioned in Gentoo documentation?
Is it the same as running: "icecream-create-env" ?

2.) icecream-create-env
we need to run it after we compile gcc, glibc, binutils without CFLAGS

Gentoo documentation has mentioned:

...After that you need to set ICECC_VERSION to point to the tarball(icecc environment) for arm-linux-gnu. You can create it using icecream-create-env. You probably don't want to set it permanently, just on an as-needed basis.

What does it mean "not setup permanently?

I'm still confused as to the correct setup. I don't want to compile half a day and realized the machine will not boot it because of some errors, or incorrect setup.

Once icecream is setup I think I'm stuck with it as "gcc, glibc, binutils" were compiled with CFLAGS removed, isn't it?
What if I want to disable the icecream?

[Joseph_sys]

It seems to me: /usr/bin/icecc --build-native
does the same thing as: icecream-create-env

It creates local/native environment.

Does the environment we create make a difference what CFLAGS gcc, glibc, binutils are build with?
Do we copy this environment to other boxes and environment from other boxes to local box?