Change Value of ParamInfo after adding to DynamicParameters?

I'm calling a stored proc in a foreach loop and would like to change the value of one of the parameters on each iteration. Currently, there doesn't seem to be any way to access the parameters once they've been added to DynamicParameters although from reading the source, I can see that DynamicParameters does keep an internal Dictionary. Any reason why this isn't public or if there's another way to get at the ParamInfos to change values?

Update

What I have currently:

foreach ( var fooID in fooIDs )
{
    var dynamicParameters = new DynamicParameters();
    dynamicParameters.Add( ParameterNames.BarID, barID );
    dynamicParameters.Add( ParameterNames.FooID, fooID);

    connection.Execute( ProcNames.MyProc, dynamicParameters, commandType:CommandType.StoredProcedure );
}