You will need to get back into 10.1 using the rescue disk because you will possibly need to compile the Kernel to create these modules instead of having them included in the Kernel -
This is what I did or will do when I upgrade to Slackware 11.00 using the 2.4 series Kernel.
Install/upgradepkg slackware onto the USB drive;
without rebooting compile the kernel to generate the required modules see
for the modules required
create the initrd image with the required modules;
create a boot cd, with the kernel and initrd;
test to ensure that you can boot from the cd;
do the lilo/grub, I use lilo - Slackware standard, business so that you can boot into slackware from the USB drive. This is the fun bit as if you're not careful you will overwrite the boot sector of your internal hard drive. If this happens get a live distro with testdrive-static so that you can recreate the win boot thingy on the internal hard drive.
I've been running with Slackware on a 20GB USB drive for several years upgrading through various releases in the process.