Could you show your code?
But without seeing it, I can say that all you need to do is getting an Add Local Offset node, right click on it’s Delta Location pin and hit the Split Struct Pin option, then multiply your float track’s value by -1 and plug the result into the exposed X component (or Y, depends on your orientation) of the delta location, and connect the Update output exec pin of your timeline to the Add Local Offset node.
To be able to switch the direction dynamically, you can create a new int / float type variable, and plug it into the other pin of the multiplication node where currently the value -1 is inserted.
Hope this helps 