Maybe I'm asking a stupid question, but is it possible to slipstream a Linux and
if it is, how to do it?
For example I would like to have another kernel which has support for some
PXE network adapters in order to be able to install a cluster of linux machines.
Any reference or guide will be appreciated.

You need to be more specific. Slipstreaming is a Microsoft term for mixing a service pack into a build. If you mean something else, then let us know.

If you need multiple kernels available, all you need to do is copy it to the hard drive. You can make your bootloader choose the kernel you want to run.

Well, let me try to explain myself.
I'm trying to install Mandrake CLIC 2.0 (cluster) with some old 2.4 kernel on
three identical machines with ASUS A7N266VM motherboard which has nForce2
chipset with integrated nvidia MCP network adapter.
That particular kernel doesn't have appropriate modules for this net. adapter and
I'm unable to install nodes and bring up the cluster automatically through network because
of this disadvantage.
Suppose, for example that I have a 100 machines in a cluster, it would be very annoying
to install manually node by node.
So I would like to know is it possible to change that kernel in installation CD
(to put a new kernel into a build) with some new one like it is possible to slipstream SP in win?

It depends on the changes, but it should work.

Of course you'd need to test it.

Yes, but how can I do that (put new kernel into a build)?