I can only agree with Peter on this in that you may wish to look at APS. However, I do have a question - seems dumb, but HOW do you want the system to work? You want to Schedule by Sales Order. How would this work ideally? Do you want a constrained promise date to appear on the Sales Order during Sales Order add so you can give this promise date to the Customer?
A Sales Order is just a Customer Demand from which you apply a Promise date based upon your Manufacturing capacity. Sadly the ATP abilities of JDE are based upon the unconstrained, make-to-stock, scenario. Sales Orders have no constraint. Work Orders do. The only way to ties lots of Work Orders together is with the "Parent WO" field in the F4801. However, even then it won't do anything unless the promised "Project Planning" software is ever launched.
So, to return to my question... I guess you would like the Promise Date on the Sales Order to be generated based upon the Total Constraint upon your Manufacturing Facilities? As you found, JDE isn't designed that way. The nearest it gets is the Resource Requirements Planning system that uses a Resource Profile and Forecast. Even so, this system doesn't yield dates. It just lets you know how much machine and labour time you need. The APS offering is the only way to get constrained delivery dates upon WO's and Sales Orders.
When you say 'scheduling' - does this imply that you want to change the Promise Date on the Sales Order and have this change the Request Date on all the WO's? Effectively you can do that with MRP.