TeX Live support for custom binaries

It is possible to install and use TeX Live with binaries that are not in the original distribution. The most common case for this is when you are on a platform which the original TL distribution did not support. Here are the steps:

1. Acquire the “foreign” binaries and install them (unpacked if necessary) in, say, /tmp/foobin.
2. Run install-tl --custom-bin=/tmp/foobin.
3. Add TLROOT/bin/custom to PATH. The “/custom” there is literal, and TLROOT is wherever you installed TeX Live, /usr/local/texlive/20yy by default.

Regarding subsequent TL package updates from the net: ensure that you have wget, xz, and xzdec available in your PATH; otherwise, TL will have no way to download or decompress packages. Also, there will be no updates to the platform-specific packages in TL, since the custom platform doesn't exist in the canonical TL repository.

If you want to install a second set of custom binaries (from, say, /tmp/barbin), you have to manually rename the first set, like this:

1. mv TLROOT/bin/custom TLROOT/bin/custom-foo
2. mkdir TLROOT/bin/custom
3. cp /tmp/barbin/* TLROOT/bin/custom
4. Switch your PATH between TLROOT/bin/custom and custom-foo to control which set is current.