In another post, I discussed how to build Chez Scheme from source for Debian 9 Stretch, here is how to setup SLIB.

git clone https://github.com/taktoa/slib.git
cp -fr slib /usr/share
cd /usr/local/lib
ln -sf /usr/share/slib .
chmod 777 /usr/share/slib
touch /usr/bin/chez
chmod 777 /usr/bin/chez
vim /usr/bin/chez

Edit the file /usr/bin/chez to be:

#! /usr/bin/scheme
(load "/usr/share/slib/chez.init")