rescueing require

I have a rails application running on a shared server. As I can't
install gems on it, I was going to put my own lib on the server if it
couldn't find the gem. My code was as follows (in the controller)

      require "rubygems"
      require "payment"
      $: << "/home/username/rubylib"
      require "payment"

The problem is that the rescue doesn't get processed. When it hits the
require at line 3, the app dies. I know that the code from line 5 ($: <<
...) works as I've tested it with irb as well as put it standalone in
the controller on the shared server. If the rescue were processed,
everything would be fine.

Does anyone know how to get a recovery in this situation?
Thanks in advance

If I remember correctly, gems and rails plugins have the same basic
structure (as far as loading goes) and you can unpack a gem into the
vendor/ directory. This would seem to be easier than what you're
trying here...