in your preferred directory (~/guix/unpackaged/ in the example below)
and then:

--8<---------------cut here---------------start------------->8---

guix shell -f ~/guix/unpackaged/tissue.scm -- tissue help

--8<---------------cut here---------------end--------------->8---

The first time the package(s) gets compiled, so it'll take as time as
needed, from the second time onwards the guix shell cache will do its
job and the command will run immediatly.

With this trick you can use Guix to install tissue [1] and use it for
your project - or tissue issues [2] - before tissue is packaged in Guix.

«One Guix to rule them all» :-D

Happy hacking!

[1] even on foreign distros obviuosly

[2] web view: https://issues.genenetwork.org/?type=open-issue

-- 
Giovanni Biscuolo

Xelera IT Infrastructures