how to use slirp to build packages without sudo?

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http://askubuntu.com – A comment to the answer of the question: Is it possible to run pbuilder without root privileges? says this, If Slirp works out of the box and doesn’t require root (for writing to /etc and adding your user to a group) to set up, why would anyone not use Slirp for this? Does the commenter mean to use slirp to install and manage packages? How do I use slirp for this? I tried google, but could not find useful information. I cannot add comment so I asked new question. (HowTos)