Yes it is possible.

You sure can. It requires knowing when you get to the brink of cuming and head teasing, but its totally possible. Most stages of per come are early on and it is still clear. You can put your tongue on it and pull away and it will string out to you a ways. The closer you get to the cuming the thicker it gets. Using your tongue to tease the under head (where the helmet splits) at the point of cuming is the best tease. It can make a man shake for as long as you do it and will leave him on the brink of cuming. At some point the pay load must cum though and it is rewarding.

Nice! Gotta know, if someone simply licks and sucks at the head, can you deliver a precum discharge for a long sexing session?

How?

You just made my cock really hard.