Thanks Rlos for your reply and confirmation on the code snip-it. We have success now!
Sadly, the PSOC 6 arduino header isn't 100% compatible. On the shield I was planning to use, (it's got 4 nice weather sensors), I lifted A4/A5 so the i2c bus wouldn't be affected by pins 10.4/10.5 on the psoc, along with shorting 5.0v to 3.3v and lifting 5.0v on the shield (so internally it's now just running at 3.3v). While this works on a 3.3v arduino, no luck here.
So today i switched to just using one of the same i2c sensor's running at 3.3v, with a very simple 4 wire break out board (scl/sda/gnd/vcc), it just works fine.