To get this extension in your TAO installation, modify your root composer.json as follow:
"repositories": [
...,
{
"type": "vcs",
"url": "https://github.com/infosign/tao-theme-base.git"
}
],
require" : {
...,
"infosign/tao-theme-base": "dev-master"
],
composer update infosign/tao-theme-base --prefer-source