Resistor calculation complicated?
TL;DR; You can't power that thing off the Raspberry Pi power pins. Build a proper high power LED driver with a separate power supply.

The voltage from the Pi (even the 5V pins) will be far too low to get any reasonable light out of it - LEDs are diodes with a forward voltage which has an exponential relationship with current - if you drop the forward voltage by two thirds, the current is going to drop by several orders of magnitude, and hence the light output will too. 

Back of the envelope calculation, if you run a 9V LED from a 3.3V supply, you'll have a current in the order of nanoamps (10-9 Amps vs the required 10-1 Amps). Essentially you 3W LED effectively becomes a 3nW LED.

If you try to use a boost converter to bring the voltage, you're going to increase the current requirements proportionally. So if you triple the voltage to 9.9V, you'll need roughly 1A from the Ras Pin to power it. The 3.3V regulator on the Pi is not designed to handle that kind of external load. Neither is the 5V power for that matter.