Thrust123... To answer your question, YES. Because you are making a Scenario, you can place the Resources where you want them on the map.
You can set the Wonder where it has No Required Resource and it will Auto-produce the Unit according to the number of turns you set in the editor.
I mentioned the Resource because it adds another aspect for more control IF needed.
I cannot know when you want the Unit to be produced or the number of turns you have in your game.
IF you do not require a Resource to help set up when you want the unit to be "Built" for timing... then simply place the Wonder and set the number of turns it will Auto-produce the unit you want.
I am certain you understand the timing factor so if you only want one Unit in your game just do the math and have it Auto-produced when you want and without enough time in the game to produce another one. A resource can allow you to be more specific IF needed because the number of turns and when the Resource becomes available dictate exactly when the Unit will be "Built". You could set a unit to be produced every turn but the unit will not be produced until you gain the Resource.
It can be confusing... Units can require a Resource to be Directly Built but IF a Unit is Auto-produced by a Wonder or Improvement, it is the Wonder or Improvement that requires the Resource to be Functional or able to Produce the Unit.
That said, you could have the same Unit in a Game where it is Both Auto-produced by an Improvement or Wonder as well as able to be directly Built. I have this in EFZI2 Complete. The difference is if the Unit requires a Resource to be directly Built, you must have the Resource flagged as a Requirement for the Unit. IF an Improvement or Wonder is set up to produce a Unit they can with No Resources but IF the Pre-placed Improvement or Wonder are set up to Require a Resource to be able to Build them Directly and you Pre-place them... You have the Improvement or Wonder Before the Required Resource is available. This is what prevents the Improvement or Wonder from being able to Produce the Unit because the Improvement or Wonder could Not have been built without the Required Resource to Built it. This, by the way, is also the reason why the Advisor will state that the Pre-placed Wonder is being Built when you start the game... it is programed to Build Only... Not understand Pre-placed Wonders.
It is the Resource that is set as a Requirement for the Improvement or Wonder that will dictate when the Pre-placed Improvement or Wonder actually exists and can produce Units. But remember all flagged settings will be in affect other than producing Units... This is all simply taking advantage of the programming. It exists yet cannot
It is as if the Improvement or Wonder is there, yet cannot be there because it required a Resource to be Built in the first place. The programming allow us to take advantage of the Flags that will work from the start for Pre-placed Improvements or Wonders but the the same programming does not allow the production of Units from an Improvement or Wonder that could not be Built because the Required Resource had Not been gained.
Hope I am explaining this where it makes any sense.