After trying to use other i2c libraries (trying to get an i2c lcd running) I gave up and searched for spin examples that I could convert to C for SimpleIDE.
It is fairly small - not a lot of 'extra' functions (like eeprom specific routines) - just the basics needed to start an i2c bus and read/write to devices on it.
So far I have only tested it on PCF7584's and the LCD with this same chip. But I am expecting that it should work on any i2c device - I will be playing with it and other i2c devices in the next week or so... I will update it as needed.