No, you can't (with packets, at least.)
Your character's velocity and speed are 0 on the serverside. In fact, the server doesn't even know your character has
velocity or speed, but rather it only cares about the player entity's position. That's why some shitty freecams tend to "freeze" your character server-side, which allows staff to detect your hacks via water buckets (the water doesn't push your player because the server doesn't try to apply a velocity to your character to move it.)
As you can probably guess, the server's understanding of your speed/velocity comes from the position packets your client sends, the delta changes between each consecutive position and their related delta times. In other words, your position on the server is entirely*
dictated by your player's position on your client, which is why fly hacks are still
possible to use on vanilla servers and unprotected Spigot servers.
If you want to "increase" your speed server-side, you make your character run faster client-side. It's as simple as that.
As to the method to actually achieve that, just look at how speed potions increase your running speed. I don't even have Minecraft's decompiled source at the moment, so I wouldn't know what class you need to begin with.
*There are measures to counteract cheats, obviously. For example, travelling millions of blocks instantly tends to freak the game out and consequently kick you. Or if you travel a certain amount in the air without descending (which ultimately increases the fall damage you get when you land), the game will kick you for flying. Again, it depends on the calculated velocity the server creates using your client's position packets and delta times.
Edited by DeCoolJB, 11 January 2017 - 12:51 AM.
Jesus loves you.