  The fusion-by-diffusion model proposed by Swiatecki {\it et al.} [Phys. Rev.
C71, 014602 (2005)] has provided a simple and convenient tool to estimate
evaporation residue cross sections for superheavy nuclei. I extend this model
by taking into account deformation of the target nucleus, and discuss the role
of orientation of deformed target in hot fusion reactions at energies around
the Coulomb barrier. To this end, I introduce an injection point for the
diffusion process over an inner barrier which depends on the orientation angle.
I apply this model to the $^{48}$Ca+$^{248}$Cm reaction and show that the
maximum of evaporation residue cross section appears at an energy slightly
above the height of the capture barrier for the side collision, for which the
effective inner barrier is considerably lower than that for the tip collision,
thus enhancing the diffusion probability. I also discuss the energy dependence
of the injection point, and show that a large part of the energy dependence
found in the previous analyses can be attributed to the deformation effect of a
target nucleus.
