Use the bootdisk you have made during the install and boot with the option
(assuming the linux drive is slave, and linux lives at partition 1)
If the kernel version of your bootdisk doesn't match the one on your linux install it will throw lots of failed module dependency warnings at you, but just ignore them.
Then, edit /etc/lilo.conf and assure yourself that linux is booted from /dev/hdb1 (again, assuming the linux drive is slave, and linux lives at partition 1)
save lilo.conf and as root, run lilo
it should display something like