This sort of stuff is a little beyond me but I had a look around anyways.
Seems you can activate Chakra from your end....
http://stackoverflow.com/a/7367729/189093
...BUT, its not made to be completley compatible with all features of IActiveScript....
http://stackoverflow.com/questions/17472638/error-adding-scriptitem-codeonly-symbol-using-ie9-js-engine-chakra
...they have a new way of exposing the engine to win32 apps, but thats not the same is it and I would guess would add alot of work for you, so no go.
OhWell, its still cool π

JScript is slow, but you knew that ;)
This is a reply to Vlasta for this thread....
http://www.rw-designer.com/forum/2636
...Im putting it here as to not pollute that thread. Got the feeling they wanted just script posts in there.
Figured it was windows scripting and hoped aswell that installing IE 11 would speed it up, but alas, no.
Bumma too, as the new IE has some serious speed like all the browsers now...still lacking heaps but atleast their JS speed is up (nice to see webgl in there aswell and with massive speed! https://www.scirra.com/blog/125/internet-explorer-11-webgl-and-more ).
Be awesome if you could change it to something like spidermonkey (or woteva its called now) or V8 but Im guessing that would be a massive pain so no fuss. Even as it is the JS in the great app is just a joy.
So if its windows scripting (that I have no experience with), does this mean I could do things like bring up a file selection dialog and get them to open a file? One thing Id love to make if possible is a way to import a sprite off a sprite sheet packed with TexturePacker. This would involve opening a json file, parse it, and then bring up something asking which sprite they'd like to import and if bringing that up is a pain then just create a layer with the right name for each sprite. The cutting the images out of the sheets looks easy enough.
Ohwell, hope I dont come across like Im unsatisfied, Im extremely impressed with this app as free and cant believe Ive only just noticed it....very well done, thank you.
PS. WebP support! Awesome! Dont see that often enough. I use them when I make Chrome themes and sometimes I accidently save images off the web as webP and its great to have this (I have a little homemade web accelerator that recompresses all images as webP, Im dial up).