it should be possible to compile it with 3.10 kernel as well. However, there is already newer driver written by Nick at https://github.com/DIGImend/huion-driver. Could you try that one instead? It should be possible to compile it outside of the kernel tree (in other words, you shouldn't need to recompile the whole patched kernel).
Wondering if this patch is compatible w/ the Slackware 14.1 3.10.17-smp kernel. My /lib/modules/3.10.17-smp/kernel/drivers/hid folder contains many hi-xxx.ko files, not up to speed on how this system writes lib files.