You don't need drugs to boost your self confidence, Ankesh. Apparently you've glossed over, or didn't think through to the ultimate possibilities in the oxytocin links, or your question would not have been put forth as stated.
Messing with the hormone levels in the body inevitably affects other, seemingly unrelated, actions in the body. Just as no man is an island, no hormonal action in the body is a stand-alone event. Re-read the links and note the under-stated but still mentioned, adverse events and then follow through on those to learn more before you begin experimenting. You may decide the ultimate risks aren't worth it. At least, I hope you do.
The best way to increase self-confidence is to gain gradual, success upon success, in a given situation. This can be in closely monitored and guided group experiences, if necessary, or simply by exposing oneself to the specific situation in real life, go a bit beyond your comfort point each time until you've built up your confidence to handle the situation. Rinse and repeat.
Anyone who tells you there's a 'shortcut to social success (or any other kind of success)' has another motive...and it may not be what you hope or think it is.