I'm not familiar with Minecraft Forge, but Every 3D game engine particle system should have a set of objects or helpers that interact with your particle systems affecting them by forces. For example gravity can be a linear force field given a vector or radial force field given a position.
You need to link your particle system with a force field around a line or cylinder while the force should point inside to the cylinder; Then spawm particles around the center (1.5 character width aprox.) perpendicular to the force field.
If your game engine doesn't support those type of force field try following trick with similar effect:
Spawn a bunch of particle system around a circle on the base or your character then rotate these positions where the particles are spawn (posX, posY, posZ). The effect is like a fountain, with spirals.
Last option, because I think this will slow down performance, if you have access to modify particles velocity in real time implement the solution given by @Alex:Taking a normalized vector from particle position to character position vertical axis, multiply it by acceleration, then add it to current particle velocity vector.