You'll need an Arduino to act as the brains, and translate your sensors into something that Flotilla can understand. But what you propose certainly isn't impossible!
Your best bet for a single value is to spoof either a Dial, or a Slider. These use i2c slave address 0x15 and 0x16 respectively and each have two registers at 0x00 and 0x01 which represent the MSB and LSB of their 16bit values.