  We study the $B \to Kl^+l^-$ semileptonic decay process in three-flavor
lattice QCD. We analyze several ensembles generated by the MILC collaboration
at different lattice spacings and sea-quark masses. We use the asqtad improved
staggered action for the light quarks and the clover action with the Fermilab
interpretation for the heavy $b$ quark. We present preliminary results for the
vector current induced form factors for a range of kaon energies. Our analysis
includes chiral and continuum extrapolations based on SU(2) staggered \chi PT.
