  Given a mixed Hodge module E on a scheme X over the complex numbers, and a
quasi-projective morphism f:X->S, we construct in this paper a natural
resolution of the nth exterior tensor power of E restricted to the nth
configuration space of f. The construction is reminiscent of techniques from
the theory of hyperplane arrangements, and relies on Arnold's calculation of
the cohomology of the configuration space of the complex line. This resolution
is S_n-equivariant. We apply it to the universal elliptic curve with complete
level structure of level N>=3 over the modular curve Y(N), obtaining a formula
for the S_n-equivariant Serre polynomial (Euler characteristic of H^*_c(V,Q) in
the Grothendieck group of the category of mixed Hodge structures) of the moduli
space M_{1,n}. In a sequel to this paper, this is applied in the calculation of
the S_n-equivariant Hodge polynomial of the compactication \bar{M}_{1,n}.
