Passing a structure out is as easy as using a period in the
variable name in your SetVariable() call.
For example,
pRequest->SetVariable ("SPP_zResults.bHadErroredPts", "0");
pRequest->SetVariable ("SPP_zResults.dMax",
"3.14159265");
Passing a struct in may be just as easy, I haven't ever
needed to try it.
Let us know if it works.