Install an ebuild

The ebuilds I offer here or on the gentoo bugzilla are not managed by Portage. So they have to be downloaded and installed manually in a custom Portage (the "portage overlay").

We suppose here that the software to install is software and that the category of the ebuild is category. For example, for TiEmu, software is tiemu and category is sci-calculators.

Here is the way to go:

Verify that you have an portage overlay defined in your make.conf. Generally, you should have:
```
PORTDIR_OVERLAY="/usr/local/portage/"
```
If they doesn’t exist, create the directories of the ebuild path:
```
mkdir -p /usr/local/portage/category/software
```

Download the ebuild and copy it in his directory:

cp software-X.XX.ebuild /usr/local/portage/category/software/

If some patch are provided or other files are joined to the ebuild, copy them to the "files" directory:

mkdir -p /usr/local/portage/category/software/files
cp file1 file2 file3 /usr/local/portage/category/software/files/

Create the manifest of the ebuild :

ebuild /usr/local/portage/category/software/software-X.XX.ebuild digest

And now, emerge !
```
emerge software
```