Different row delimiter in Flat File Connection Manager

When creating a flat file connection manager, the default row delimiter is {CR}{LF} and there are seven othe choices. What if all these choices are not suitable for my usage and I want to create my own, is there a way to do it? For example, I want to use ##&&** as a row detimiter.
If there is a way, can I define it as a parameter or variable so I can pass it to the package before the execution? This way I can choose when to change the row delimiter.
Any help on this is very much appreciated.
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