I managed to setup a bootsplash for my Slackware 9.1 with 2.6.5 kernel but the progress bar doesn't work.
Do you know how could I fix this?
Thanks!

Maybe the startup scripts are not installed properly. Can you tell us what exactly were your steps when installing the bootsplash? I only use the bootsplash to display the penguin in the background and haven't tested the progressbar.

added the patch for 2.6.5 kernel on my kernel, them recompiled it with initial ram disk support and bootsplash.
I have downloaded all the software I needed from bootsplash.org and create the initrd.splash with "/sbin/splash -s -f /etc/bootsplash/themes/Linux/config/bootsplash-1024x768.cfg >> /boot/initrd.splash"
After that I configured lilo by changing vga to 791 and adding a new entry:
image = /boot/bzImageWithBootsplash
root = /dev/hda1
label = SlackwareWithBootsplash
initrd = /boot/initrd.splash
append = "splash=silent"
read-only
Then i reruned lilo and this was all

This is not enough to have the progress bar working. It requires some scripts to work. Why don't you read the instructions for Slackware at madpenguin.org ? And there was also a thread in this forums.

I done more search on the net and downloaded bootsplash utility, modified rc.S, rc.M and rc.6 and now works great.
Thanks!