Is the radiation on IO's surface directional? I know that magnetospheres redirect solar radiation into the poles of a planet, but since IO is in Jupiter's magnetosphere does that mean that solar radiation is redirected across the planets surface like wind on earth?
 A: 
Is the radiation on IO's surface directional?

Radiation comes in many forms and I think you may be misunderstanding a few things.  For instance, the primary radiation used to define a solar flare are electromagnetic x-rays, specifically a localized enhancement of x-rays above some defined threshold.  These are photons that effectively do not care about magnetospheres.
Solar flares are often associated with another type of radiation that arrives slightly after the x-rays, called solar energetic particles (SEPs).  These are highly energetic (i.e., very fast) particles with a finite mass and most of them carry electric charges, so they do care very much about the magnetic field in the solar wind and near planets.  However, the most energetic of these, the ~1 GeV protons, are so energetic that their gyroradius is larger enough to allow them to penetrate all the way into Earth's atmosphere.  As an aside, such energetic events are often associated with energetic neutrons which do not care about the magnetic field and make it to the Earth's surface, producing what are known as ground level events (GLEs).
So the charged particles make up part of the collective ionized gas called a plasma.  The plasma in the Jovian magnetosphere is indeed directional in that it's dynamics are governed by the magnetic field.
Io is unique in that it is volcanically active due to the tidal forces exerted on it by Jupiter.  Thus, it spews initially neutral particles into the magnetosphere, some of which are ionized.  This forms a belt around Jupiter called the Io plasma torus.  This is made of neutral and ionized gas that orbits Jupiter (neutral) or drifts around Jupiter (charged) as part of the adiabatic motions of charged particles.

I know that magnetospheres redirect solar radiation into the poles of a planet...

This isn't entirely correct.  The charged particles (which are a type of ionizing radiation, yes) that are directed toward the magnetic poles of a magnetized body in the solar wind do not come directly from the solar wind.  They usually come from the geomagnetic tail of the magnetosphere (e.g., the electrons which fuel the aurora are accelerated from the geomagnetic tail to the poles).

but since IO is in Jupiter's magnetosphere does that mean that solar radiation is redirected across the planets surface like wind on earth?

The solar wind doesn't directly enter magnetospheres, it is redirected around by the bow shock and magnetopause.  It can indirectly enter through magnetic reconnection exhausts and reconnection in the tail, but it doesn't just sail in on ballistic trajectories.
