-Until such time as MPPE support ships with kernels, you can use
-the Linux 2.2 or 2.4 implementation that comes with PPPD. Run the
-ppp/linux/mppe/mppeinstall.sh script, giving it the location to your
-kernel source. Then add the CONFIG_PPP_MPPE option to your config and
-rebuild the kernel. The ppp_mppe.o module is added, and the ppp.o module
-(2.2) or ppp_generic.o (2.4) is modified (unfortunately). You'll need
-the new ppp.o/ppp_generic.o since it does the right thing for the 4
-extra bytes problem discussed above.