How to install PPTP server on RN312?

Hi,
I want to install a PPTP server on my NAS I have running at my parents. The installation went smooth until I realized I don't have the needed kernel modules installed. The customized kernel in RN312 contains neither MPPE or PPP support.

I followed this guide, but it is for older readyNAS HW and kernel version.
http://www.readynas.com/forum/viewtopic.php?f=35&t=33132&p=182215&hilit=MPPE#p182215

root@NAS-312:/# uname -a
Linux NAS-312 3.0.93.RNx86_64.2.1 #1 SMP Mon Sep 30 11:46:22 PDT 2013 x86_64 GNU/Linux

root@NAS-312:/# modprobe -l
kernel/fs/ufsd/ufsd.ko
kernel/crypto/cryptodev.ko
kernel/drivers/media/video/videodev.ko
kernel/drivers/media/video/v4l2-int-device.ko
kernel/drivers/media/video/v4l2-compat-ioctl32.ko
kernel/drivers/media/video/v4l2-common.ko
kernel/drivers/media/video/uvc/uvcvideo.ko
kernel/drivers/media/rc/rc-core.ko
kernel/drivers/media/rc/nuvoton-cir.ko
kernel/drivers/media/rc/lirc_dev.ko
kernel/drivers/media/rc/ite-cir.ko
kernel/drivers/media/rc/ir-rc6-decoder.ko
kernel/drivers/media/rc/ir-rc5-decoder.ko
kernel/drivers/media/rc/ir-nec-decoder.ko

1) As I understand I need to get these files for my kernel. Anyone know how I can get them for my kernel?

drivers/net
•ppp_async.ko
•ppp_mppe.ko
•ppp_generic.ko
•slhc.ko
drivers/crypto
•sha1.ko
•arc4.ko

2) How to safely compile my kernel with them?

3) Anything I have missed? Can I do this in a reversable way? I don't want to loose all my content on the NAS while playing with the kernel.

/
Elast