I can't get io/wait installed.  The main problem is that it doesn't
install out of the box.  The second problem is that I don't know how
to do it manually.

Here's the relevant part of the output from running 'make install'

installing io/wait
make[1]: Entering directory `/home/gavin/Projects/ruby18/ext/io/wait'
make[1]: Nothing to be done for `install'.
make[1]: Leaving directory `/home/gavin/Projects/ruby18/ext/io/wait'

Cheers,
Gavin