I found a solution
After installing the Server-software, I was asked to remove CD/floppy and reboot.
Instead I rebooted on the emergency boot floppy and wrote the boot-string again:
boot: accept = mem=exactmap mem=640K@0 mem=254M@1M
This made the system run fine.
After this I logged in as "root" and changed the file: "/etc/lilo.conf" to include the mem-information. The right place would properply be in "/etc/e-smith/templates/etc/lilo.conf/", but I don't know where to put the lines in template-files.
It (/etc/lilo.conf) now looks like this:
-------------------------------
prompt
timeout=50
default=SMEServer-up
boot=/dev/ida/c0d0
map=/boot/map
install=/boot/boot.b
message=/boot/sme_server.pcx
linear
image=/boot/vmlinuz-2.4.20-18.7smp
label=SMEServer-smp
initrd=/boot/initrd-2.4.20-18.7smp.img
read-only
root=/dev/ida/c0d0p3
append=" mem=exactmap mem=640K@0 mem=254M@1M"
image=/boot/vmlinuz-2.4.20-18.7
label=SMEServer-up
initrd=/boot/initrd-2.4.20-18.7.img
read-only
root=/dev/ida/c0d0p3
append=" mem=exactmap mem=640K@0 mem=254M@1M"
-------------------------------