I was told to reinstall my host OS in order to keep working with LFS because im pretty sure i had actually installed a package or two on my host Linux and thus rendered everything useless... at any rate, i was considering this... I already have windows on one partition... i have mandrake 8.1 on a few others... i was thinking about this:

how about also setting up a small mandrake partition by itself and do the compiles and installations on LFS from that particular one rather than risk corrupting my major mandrake install... if i did, how do i set up a triple boot for that?

If you follow everything in the book then you really won't mess up your host distribution. But It won't hurt to install another distribution to use just to build LFS. Basically all you have to do is install Mandrake again. Make sure you choose expert mode. And just give it one partition to install on. And make sure you either disable lilo/grub or install it to the partition you put the new installation on. Then update your original bootloader and add another entry for the new installation.

while editing lilo.conf can you use the same kernel image to boot the extra mandrake as you do your regular one?

Yes that's no problem. Just make sure that in that lilo.conf section you enter the right root partition.

Keep in mind though that if the other Mandrake is a different version, it's configured for a different kernel version so loading modules won't work. But if the Mandrake's are configured for the same kernel (say you installed the same Mandrake version from the same cdrom) then this'll be a good way to do it. It'll save you some disk space.

Personally I hardly ever use modules so I don't really concern myself with this and therefore I use one kernel to boot pretty much every Linux system I have (LFS and non-LFS)