[R-sig-Geo] How to calculate a cross-correlogram based on Morans I

[Jens Floeter]

  Dear list members,

i need a hint - i am stuck on my search for a function.

I would like to calculate cross-correlograms between two variables 
(predator and prey densities) and use this as an index of spatial overlap.

I used the spdep pakcage and use e.g.

sp.correlogram(xy.data.nb, prey, order = 5 , method = "I", 
zero.policy=TRUE, style = "W")
sp.correlogram(xy.data.nb, predator, order = 5 , method = "I", 
zero.policy=TRUE, style = "W")

to calculate the (auto-) correlograms for predator and prey individually.

But how do i combine them to calculate the cross-correlogram ?

Any hint would be highly appreciated...

Best wishes !
jens