Using custom Machinepack in treeline.io

I'm currently testing the beta of treeline.io, firstly it's awesome.

Secondly, i'm struggling with how i would add a custom Machinepack. I have one i need that's very specific to an application i'm testing that it doesn't make sense to add to NPM/Github.

Now if this was a sails app i could manually add it to api/machines, but that get's overwritten locally whenever i restart my treeline.io application.

Now i have the option of creating a new machine directly on treeline.io, but i can't then sync that locally to edit it, or actually get at the underlying code of the machinePack (i know that's kinda the point, but i am still always going to need to do some custom things).

Perfectly possible this just isn't quite there yet given the beta nature of things, just wanted to check i wasn't missing something!

Thanks

Gareth