i'm running slackware 9.1 too, two systems, one with an audigy soundcard and the other with a soundblaster sb 5.1.
i followed these instructions:
http://www.mail-archive.com/alsa-use.../msg07365.html (alltough i took the new drivers 0.9.8 (but these work too: 0.9.6, 0.9.7). one remark: i had to configure the drivers with the disable-verbose-printk option (i don't know for what this is needed), i.e.
in the alsa-drivers-0.9.8 directory you'll have to execute the following command:
"./configure --disable-verbose-printk"
else you won't be able to insmod your new drivers.
i don't know how far this will help you, so i would take a look at the mailing-list-archive too, you for sure find something:
http://www.mail-archive.com/alsa-user%40lists.sourceforge.net/