arc4 and xen domU kernel

[Stefano Marinelli <postnet%dragas.dyndns.org@localhost>]

Hello everybody. I'm trying to compile the mppe-lkm module (from pkgsrc) on a 
netbsd-5 domU machine. It's needed for proper pptp termination.

The problem is: I get this message:

This LKM requires attribute ``arc4'' to be compiled in the kernel.  The
only drivers that get it compiled are the WiFi ones, such as wi(4).  An
instance of that driver in the kernel configuration file is enough to
pull the arc4 functions in the resulting kernel.

The REAL problem is: it doesn't seem I can compile something like wi(4) on a 
domU kernel. Any workaround to have the arc4 attribute on the kernel? Tried to 
look at the config, but didn't find anything (clearly) related.

Thank you,
Stefano