I suspect this homebrew interface will work with QLC+ with no software mods necessary if you set the right settings. It already supports some commercial products that use the same FTDI chip:
I used to use DMXControl on Windows for stage play FX lighting (on-stage things such as uplighters, fireplaces, illuminated signs etc.) and would just setup a presets board with virtual push buttons.
I had a quick skim through the QLC+ site but couldn't see whether it had an equivalent feature. Any thoughts? Thanks.