Registering $variables for Forumhome

[TheSupportForum]

Hello

i need help with registering some $variables for use in Forumhome
within a plugin, the variables are already registered within a admincp file

but i want to show the same data from those $variables in a plugin
for the following Hook Location: forumhome_complete

i need to output data from $whattoecho variable

so the question is how do i register this variable to work in the plugin