Pre-dating the era of Magisk, Flashtool v0.8.6.0 includes pre-configured scripts to push Superuser binaries and install custom recoveries such as:
Flashtool is a desktop application (available for Windows, Linux, and macOS) developed by the developer known as Androxyde . It serves as a Swiss Army Knife for Sony Ericsson and Sony Xperia devices. Unlike the official Sony Emma tool, which is restrictive and requires specific login credentials, Flashtool is an open-source community project designed to give power users full control over their devices. Flashtool v0.8.6.0.
Why did everyone love v0.8.6.0?