I recompiled my default kernel, but in order to be able to boot with the old kernel and not to have problem with the old kernel modules i added an -1 in the extraversion field of the Makefile.
So now the old kernel is 2.4.26 and the new one is 2.4.26-1
The old kernel modules are placed in /lib/modules/2.4.26 and the new are in /lib/modules/2.4.26-1.
My problem is that the 2.4 kernel series do not have ALSA in the source, and the alsa module are in /lib/modules/2.4.26/kernel/sound.
I tries to link this to my new directory but the kernel does not see the modules. Do i have to recompile alsa, and what about all the files that will be in common. Is there a way to just add those files:
/lib/modules/2.4.26/kernel/sound/i2c
/lib/modules/2.4.26/kernel/sound/i2c/other
/lib/modules/2.4.26/kernel/sound/i2c/other/snd-tea575x-tuner.o.gz
/lib/modules/2.4.26/kernel/sound/i2c/other/snd-ak4117.o.gz
/lib/modules/2.4.26/kernel/sound/i2c/other/snd-ak4xxx-adda.o.gz
/lib/modules/2.4.26/kernel/sound/i2c/snd-cs8427.o.gz
/lib/modules/2.4.26/kernel/sound/i2c/snd-tea6330t.o.gz
/lib/modules/2.4.26/kernel/sound/i2c/snd-i2c.o.gz
/lib/modules/2.4.26/kernel/sound/isa
/lib/modules/2.4.26/kernel/sound/isa/sb
/lib/modules/2.4.26/kernel/sound/isa/sb/snd-sb8.o.gz
/lib/modules/2.4.26/kernel/sound/isa/sb/snd-es968.o.gz
/lib/modules/2.4.26/kernel/sound/isa/sb/snd-sbawe.o.gz
/lib/modules/2.4.26/kernel/sound/isa/sb/snd-sb16.o.gz
/lib/modules/2.4.26/kernel/sound/isa/sb/snd-sb-common.o.gz
/lib/modules/2.4.26/kernel/sound/isa/sb/snd-sb16-dsp.o.gz
/lib/modules/2.4.26/kernel/sound/isa/sb/snd-emu8000-synth.o.gz
/lib/modules/2.4.26/kernel/sound/isa/sb/snd-sb8-dsp.o.gz
/lib/modules/2.4.26/kernel/sound/isa/sb/snd-sb16-csp.o.gz
/lib/modules/2.4.26/kernel/sound/isa/gus
/lib/modules/2.4.26/kernel/sound/isa/gus/snd-gusclassic.o.gz
/lib/modules/2.4.26/kernel/sound/isa/gus/snd-interwave.o.gz
/lib/modules/2.4.26/kernel/sound/isa/gus/snd-gusextreme.o.gz
/lib/modules/2.4.26/kernel/sound/isa/gus/snd-interwave-stb.o.gz
/lib/modules/2.4.26/kernel/sound/isa/gus/snd-gus-synth.o.gz
...............................................................................................
................................................................................................
/lib/modules/2.4.26/kernel/sound/support
/lib/modules/2.4.26/kernel/sound/support/pnp
/lib/modules/2.4.26/kernel/sound/support/pnp/snd-pnp.o.gz
/lib/modules/2.4.26/kernel/sound/pcmcia
/lib/modules/2.4.26/kernel/sound/pcmcia/vx
/lib/modules/2.4.26/kernel/sound/pcmcia/vx/snd-vx-cs.o.gz
/lib/modules/2.4.26/kernel/sound/pcmcia/vx/snd-vxp440.o.gz
/lib/modules/2.4.26/kernel/sound/pcmcia/vx/snd-vxpocket.o.gz
/lib/modules/2.4.26/kernel/sound/pcmcia/pdaudiocf
/lib/modules/2.4.26/kernel/sound/pcmcia/pdaudiocf/snd-pdaudiocf.o.gz

in my new kernel?

You're probably not going to be able to just force a module compiled for one kernel into a different kernel...yes, they are different. I believe that they have some "meta-info" in them that tells them what kernel they can attach to.
The best thing for you to do is to download the latest ALSA drivers and just install ALSA that way. That's probably how they did it with the original kernel anyway.

alsa-driver-1.0.8rc2.tar.bz2

I use the 2.6 generation kernel and so have always just used the kernel-source ALSA drivers. I wouldn't know how to install the modules from the alsa-project.org site but I don't think it's very difficult.

-- the dudeman

Why not install alsa-driver from sources ?
http://ftp.scarlet.be/pub/slackware/...l/alsa-driver/

Change KVERSION in alsa-driver.SlackBuild to 2.4.26-1

This worked. I used the source from the fourth slack 10 CD instead of this, because i was afraid that installing the newer driver might break the dependencies with the other alsa packages, and it worked.

Then I had a problem with nvidia. Every time i installed it for the one kernel, the installer would uninstall the previous installed driver including the module for the other kernel. I tried duplicating the source, reruning the .config and make dep for every kernel, but the installer insisted on this. I did not manage to install only the module (all the libraries of the driver besides the module are precompiled anyway). I managed to fix this by installing the the driver for the first kernel, then boot with the other kernel, move the hole modules directory of the first kernel to another directory, and reinstall the driver, so that the uninstall process of the nvidia installer wouldn't touch my precious nvidia.o module.
It was my first kernel compilation and it was pretty adventurous.
Thank you both for your help.

Wow, that is pretty adventurous!

Maybe you deserve "The Golden Penguin" award :-)