Do not snort it, period. It doesn't work at all. Do not attempt to get high on it whatsoever. It's not safe, and doesn't work. Trust me on that one.
Loperamide can be used very effectively, however, for opiate withdrawals. But, if you're trying to get high on it you will be seriously disappointed as your guts cramp with the fury of a thousand suns.
You will only need about 10-20mg (depending on your tolerance) to subside the more taxing physical symptoms of withdrawals. It takes about 3 hours to start working, and lasts for 24+ hours.
Let me answer your next question preemptively: You cannot force Loperamide across the BBB safely, or effectively.