Yes Prime, it is possible.
The 'Custom Travelling Method Plugin' system in GC's patch is the way to easily add alternative transport methods to the game implemented in GC. Even AI ships will use it, and choose other possible travelling methods to chase their target. Pratically the only thing the custom travelling methods don't support are intercepting objs at high travelling speeds, so the "warp intercept" will still be just warp intercept.
The custom travelling methods can basically be of 2 types: ship-based (like warp or slipstream) and non-ship-based (like the caretaker array and the graviton catapult). And the normal travelling type you had with GC (warp) is implemented now as one of these plugins.
GC will come in with 2 travelling methods: warp and enhanced warp (which is a faster but more dangerous/unstable warp drive), both are ship-based.
The graviton-catapult is actually not from GC, it is from the Delta Quadrant Pack. However i'm scripting it for Jb and Limey, both to help them since they kindly asked

, and to show an example of implementation of a non-ship-based travelling method. But still it will be included in the DQP, and not with GC.
With this you can add any kind of travelling method to the game, really. Only thing that will change about adding any kind of travelling method is the difficulty of making the plugin for the travelling method, since to make the plugins you will still need some python + BC scripting knowledgement.
For example making the warp and enhanced warp were incredibily easily since the code for warp was already done, it was basicly a question of "porting" it to the plugin system.
However the graviton catapult plugin was more difficult since I wrote a pratically new "travelling out" GFX sequence, which included the use of some models (which Jb and Limey made).
The most difficult part to do is the GFX sequences (for before, during and or after travelling). Other attributes as max/cruise speeds, speed scale of the travelling method to real Cs (speed of light), if a ship can drop out or change course while travelling, are pretty easily changed.
Plus the plugins included in GC are very well commented to tell what is what. Plus before releasing, along with the new readme (obviously) i'll also make an tutorial about it.