It seems that initrdxxx.img is not necessary when compiling a new kernel. If bzImage and System.map are copied into /boot and corresponding modification is make in lilo.conf or grub.conf, i think the kernel can start successfully. And if if you build your scsi drivers right into the kernel, instead of into modules, u also need not to do "mkinitrd".
I think glibc is useless for kernel compiling. Glibc is a C library which is used by user applications that needs some shared library.