Just last night i sat up past midnight to install the Zenwalk[Gnome] 5.2. I have a partition is the use to evaluate new linux distros, distro hopping is hobby 
I install Zenwalk in the partitions sda7(/boot) sda8(/) sda9(/home) and sda10(swap). All went really smooth. And i did not choose to install lilo on sda.
Sadly Zenwalk has not switched grub.(On need to look up why!). Now i have Ubuntu HardyHeron also installed which i hardly switch, is almost a constant on my HP500 laptop. This article is more of a personal reference, but i could also be helpful for the needy 
This was was my ordeal to get Zenwalk up and running from grub’s menu.lst on my Ubuntu. I went ahead and added the following lines to the end of menu.lst file to represent my Zenwalk partition…
# Zenwalk Linux title Zenwalk Linux root (hd0,6) kernel /vmlinuz root=/dev/sda8 vga=0x31A video=vesafb:mtrr,ywrap splash=silent initrd /initrd.splash
Note for those who have little idea about entries…
(hd0,6) means look for the files on the first(index 0) physical hard drive in the 7th partition(indexing starting from 0). What files? The kernel image file and the init file.
In the kernel line make sure the the “root=” points to the where your “/” resides in, in my case the /dev/sda8 partition.
NOTE: make sure you make backup of the existing menu.lst file before you make these changes
