There are two kernels (bzImage and bzSafe), bzImage is experimental one and bzSafe is default.
Copy your testing kernel to bzImage and run # grub-set-default 1
After rebooting your new kernel is trying to boot, if anything goes wrong bzSafe is selected after new reboot.
If you like new kernel, simply copy bzImage to bzSafe …

– This is very friendly grub.conf for server –

default saved
timeout 1
fallback 0

title=Kernel Safe
root (hd0,1)
kernel /boot/bzSafe root=/dev/hda2
savedefault

title=Kernel Experimental
root(hd0,1)
kernel /boot/bzImage root=/dev/hda2
savedefault 0

– This is very friendly grub.conf for server –
Change (hd0,1) and root=/dev/hda2 to suit your system configuration, have fun ;-)