Let’s see how.
First of all look for VirtualBox source code on you machine, i will assume /usr/src/virtualbox to be the right directory name.
After that make sure to have all the necessary to build software, but if you have just compiled your kernel i doubt you need something you don’t already have.
Finally edit your “local boot scripts” file (/etc/rc.local or /etc/rc.d/rc.local … i leave to you finding which one is already present on your system) and append to it the following code:
VBOXOK=$(find /lib/modules/$(uname -r)/ -name 'vboxdrv.ko')
if [ "$VBOXOK" = "" ]; then
cd $VBOXDIR && \
make clean && \
make && \
Now every time you system boot it will check if the kernel modules for VirtualBox are present and build them if it has to.