Monkeysphere and Monkeysign ebuilds are available in gentoo as app-crypt/monkeysphere and app-crypt/monkeysign respectively. Note that you need to enable ~arch by adding app-crypt/monkeysphere to package.accept_keywords in order to install.

  # echo "app-crypt/monkeysphere" >> /etc/portage/package.accept_keywords
  # emerge app-crypt/monkeysphere
  # echo "app-crypt/monkeysign" >> /etc/portage/package.accept_keywords
  # emerge app-crypt/monkeysign

msva-perl and xul-ext-monkeysphere is currently available in a more experimental repository maintained by Kristian Fiskerstrand. This repository is available through layman.

 # emerge layman
 # layman -a k_f