I actually didn't install the NerdPack and was just playing whack-a-mole on the dependencies until it built. Here is what I ended up with on RC1:
mkdir packages
cd packages/
wget https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/linux-5.9.13.tar.gz
mv linux-5.9.13.tar.gz linux-5.9.13.tgz
cd /usr/src/
mv linux-5.9.13-Unraid/ linux-5.9.13-Unraid_orig
tar zxvf ~/packages/linux-5.9.13.tgz
ln -s linux-5.9.13 linux
cp -rf linux-5.9.13-Unraid_orig/* linux
cp -f linux-5.9.13-Unraid_orig/.config linux
ln -sf /usr/src/linux/include/asm-generic /usr/include/asm-generic
ln -sf /usr/src/linux/arch/x86/include/asm /usr/include/asm
ln -sf /usr/src/linux/include/linux /usr/include/linux
cd /root/
wget http://slackware.cs.utah.edu/pub/slackware/slackware64-14.2/slackware64/d/bison-3.0.4-x86_64-1.txz
wget http://slackware.cs.utah.edu/pub/slackware/slackware64-14.2/slackware64/l/ncurses-5.9-x86_64-4.txz
wget http://slackware.cs.utah.edu/pub/slackware/slackware64-14.2/slackware64/d/gcc-5.3.0-x86_64-3.txz
wget http://slackware.cs.utah.edu/pub/slackware/slackware64-14.2/slackware64/l/mpfr-3.1.4-x86_64-1.txz
wget http://slackware.cs.utah.edu/pub/slackware/slackware64-14.2/slackware64/d/cmake-3.5.2-x86_64-1.txz
wget http://slackware.cs.utah.edu/pub/slackware/slackware64-14.2/slackware64/d/make-4.1-x86_64-2.txz
wget http://slackware.cs.utah.edu/pub/slackware/slackware64-14.2/slackware64/d/guile-2.0.11-x86_64-2.txz
wget http://slackware.cs.utah.edu/pub/slackware/slackware64-14.2/slackware64/ap/bc-1.06.95-x86_64-3.txz
wget http://slackware.cs.utah.edu/pub/slackware/slackware64-14.2/slackware64/l/elfutils-0.163-x86_64-1.txz
wget http://slackware.cs.utah.edu/pub/slackware/slackware64-14.2/slackware64/d/gdb-7.11-x86_64-1.txz
wget http://slackware.cs.utah.edu/pub/slackware/slackware64-14.2/slackware64/d/guile-2.0.11-x86_64-2.txz
wget http://slackware.cs.utah.edu/pub/slackware/slackware64-14.2/slackware64/l/gc-7.4.2-x86_64-3.txz
wget http://slackware.cs.utah.edu/pub/slackware/slackware64-14.2/slackware64/l/libunistring-0.9.3-x86_64-1.txz
wget http://slackware.cs.utah.edu/pub/slackware/slackware64-14.2/slackware64/d/python-2.7.11-x86_64-2.txz
installpkg gc-7.4.2-x86_64-3.txz
installpkg gdb-7.11-x86_64-1.txz
installpkg guile-2.0.11-x86_64-2.txz
installpkg libunistring-0.9.3-x86_64-1.txz
installpkg python-2.7.11-x86_64-2.txz
installpkg bison-3.0.4-x86_64-1.txz
installpkg ncurses-5.9-x86_64-4.txz
installpkg gcc-5.3.0-x86_64-3.txz
installpkg mpfr-3.1.4-x86_64-1.txz
installpkg cmake-3.5.2-x86_64-1.txz
installpkg make-4.1-x86_64-2.txz
installpkg guile-2.0.11-x86_64-2.txz
installpkg bc-1.06.95-x86_64-3.txz
installpkg elfutils-0.163-x86_64-1.txz
cd /usr/src/linux
make menuconfig
make modules_prepare
export CONFIG_STAGING_APEX_DRIVER=m
export CONFIG_STAGING_GASKET_FRAMEWORK=m
make M=/root/apex/
insmod gasket.ko
insmod apex.ko
lsmod|grep apex
mkdir /boot/config/drivers
cp /root/apex/gasket.ko /boot/config/drivers/
cp /root/apex/apex.ko /boot/config/drivers/