The problem is not the sql language here--it is how these things are executed. You pass SQL off against a database engine for parsing/planning/query caching. All of which is an internal binary operation to that database engine and which has no reason to be cross-platform compatible.
I understand the IT staff's position--I would not let some random contractor come in and start inserting data into my line of business systems without at least a long history with them. Especially if it s a proprietary package not meant to be touched by human hands.
What you probably want to do here is make a 3rd database--effectively your data warehouse. Then use an ETL tool (such as Sql Server Integration Services) to pull data from both databases into the data warehouse, then do whatever reporting and validation from there.
What is an opcode and how does it have to do with any of this?