You could try one or all of these (same authors):
Dan Edidin and William Graham:
Algebraic cycles and completions of equivariant K-theory here
Riemann-Roch for equivariant Chow groups here
Equivariant intersection theory here
You could try one or all of these (same authors):
Dan Edidin and William Graham:
Algebraic cycles and completions of equivariant K-theory here
Riemann-Roch for equivariant Chow groups here
Equivariant intersection theory here