@ssmusoke, the best way to do this would be to add these to a new data set within your report, and then you would have access to this data within your Excel template just like any other report data.
@ssmusoke, I would just create a custom DataSetDefinition and corresponding evaluator yourself. You can have 0-N configuration properties on the definition (based on how configurable you want to make it), and then you simply need to implement the “evaluate” method on your evaluator and construct and return a SimpleDataSet that contains the data of interest.