In June 2016 Konstantin sent me a link to a Japanese website: http://soltec.exblog.jp/24074967/ . I found that Google Translate provide sufficient English text to allow me to work out what he was up to.
The article (part 3 of a series) describes how the author fitted a SATA socket to the circuit board adjacent to the IDE connector and some other small mechanical mods so that a SSD could be plugged in to it. He also tried fitting three drives (2 x SATA and IDE) to see if there was any priority in the order that the BIOS would boot operating systems.
Part 1 deals with adding a wireless lan card using the Mini PCI Express connector.
Part 2 deals with fitting a SATA to mSATA convertor board.
Part 3 is actually about the t510.
In January 2019 'tos' got in touch. He had made a 'fat' t5740 by using the case from a dead t5740 to house two 3.5" drives which was then mated with a functional t5740 that had been modified to provide the necessary 12V on the SATA interface. The article is in Polish, but Google translate does a good job of rendering it in English.
In October 2019 I heard from Matthew. He had used a t5740 as the basis of a NVR (Network Video Recorder) for a security camera. The software aspect was handled by ZoneMinder running on Xubuntu. You can read about it in his blog
Any comments? email me. Added June 2016 Last update October 2019