Making new Jumpgates is pretty easy. Just make your model like any other CMP, and then assign the appropriate hardpoints to it. If you read through the INI for the Jumpgate in Solararch.ini, you will figure it out very easily. Just keep in mind that you can't put the animation instructions in- we have never really cracked the animation format used by FL.
Tradelanes are a bit more problematic. You could make one pretty easily that used similar concepts as my Docking Rings in the XML Toolkit series- basically, have an object with the appropriate hardpoints out to either side of a central object. But building new ones that are circles, with new geometry... might be a bit difficult. This is because there just aren't any available SURs that would be a good fit.
I am planning to replace the current Tradelane objects with new ones for XML Toolkit Mod 1.3, that will include new SURs. I do not know if this experiment will be successful or not yet, but I intend to try it out. Right now, the SUR Export Plugin for MS3D is still in beta. It has yet to be released to the general modding public because there are a number of (fairly serious) problems with it, and there are several things it doesn't do right just yet. When we have a 100% good SUR exporter, we will be able to build many objects that are currently out of our reach. Right now, I am about the only person who has been able to consistantly make new SURs, and I am constantly stretched by my other projects, so I cannot make new ones for other people's projects, even though I'd like to