SystemRescueCd comes with four kernels which are rescuecd, rescue64 (standard kernels) and altker32, altker64 (alternative kernels). Anyway, you may want to compile your own linux kernel just because you need another driver, or you want more recent sources, or just different compilation options.
A new tutorial has been written to explain how you can compile your own kernel and add it to SystemRescueCd. This can be done from SystemRescueCd itself, so that you don’t need to have another linux system installed on your hard disk. You can also do all the compilation stuff from any other linux system installed on the hard disk, as long as you know what you are doing. This tutorial is based on SystemRecueCd-1.1.0 because this is the first version which comes with the development tools (gcc, make, …) which are required to compile the kernel. So you should not attempt to follow these instructions with an older version.
After the new kernel sources are compiled, it will be necessary to make a customized SystemRescueCd using the compiled kernel image and modules.