Well, to get to the jump-gate just discover the mines at Zone-21. Then open your Navigational Map and you should see diamonds of dust where Zone-21 is, one of the mines should have one quarter cut out of it, set a waypoint there and head towards it. Just to the East of that cut out, is an opening where you can travel freely to the gate without the intrusion of mines. This is the exact same path that the SinglePlayer missons uses.
Now, about IFCE (Ioncross Freelancer Character Editor) you first have to select a saved game from the list (by clicking on it and pressing the Edit game button). A new window should appear and will load the save game file. Now, in the bottom right of that window are two checkboxes, one of them is: Unlock all Jumpgates/holes; and the other is: Reveal entire nav map to player. Click on the Unlock all Jumpgates/holes and click on Save. Now, close all IFCE windows and launch Freelancer as usual and launch your saved game in which you editied earlier.
Hope this made it easier for you