Allows to set a particular value at a particular position into the parameter invocation order.
Because vortex_xml_rpc_method_call_add_value works in a sequential mode, it could be inconvenient under some circumstances. This function allows to skip over the sequential adding feature to implement an index-based parameter configuration.
Keep in mind that added in a index-based manner you'll have to pay attention about number of parameters, its order, etc. The function will not modify values used to perform sequential adding. This mean that sequential and index-based adding operation should not be mixed on the same method call object.
Position values should be taken to range from 0 up to number of parameters - 1. Function with 2 parameters have as available and valid positions [0,1].
Once a value is added, previous stored value, if were defined, is unrefered.
The function will not perform any operation if received values are NULL or the position provided is wrong.