I treat the eta peak in a similar way as the pion peak.  I throw single etas, flat in Pt from 2 - 25, and reconstruct the two-photon invariant mass distribution for the results.  The thrown etas are weighed according to the PHENIX cross-section as outlined here.  The mass distributions for the four pt bins can be seen below.  (I apologize for the poor labeling, the x-axis is Mass [GeV/c^2] and the y-axis is counts.)  Don't worry about the scale (y-axis.)  That is a consequence of the weighting.  The absolute scale will later be set by normalizing to the data.

These plots will later be combined with other simulations and normalized to the data.  The shape will not change.  For those interested in the errors, that can be seen below.