You can do this. I suggest connecting with Sprint international chat as the reps outside of the US are familiar with SIM cards. I did so. Took about 10 minutes of my time via chat. Paid $12 for overnight shipping. SIM was free. (Just internet search "sprint international chat" to find link).
Caution, there are MANY reports of Sprint being temporarily out of SIM cards.
One you get a SIM, insert and reboot. Go online and start the activation process. You might be transferred to chat (US) to finish the process. You will need the MEIN off the phone and the number off the card the SIM comes on (not the SIM itself).
Most folks don't have issues with activation. I did. I ended up having to go into a Sprint store to finalize activation.