Greasy Fork

Port a Firefox extension to userscript?

Is it possible to port a Firefox extension to use as a userscript? And if so, any resources/info available for doing it?

An example: one of my most used extensions (CoolPreviews, a link preview popup, by CoolIris) hasn't been supported/developed (publicly acknowledged by them https://www.coolpreviews.com/; shuttered by Yahoo purchase) for quite awhile and now Mozilla is on the verge of requiring addons to be Signed for subsequent versions, thus something not possible in this case and thus it will be blocked in the next version. Thanks in advance for your consideration and any assistance with this.
(if anyone is familiar with CoolPreviews and knows of a userscript alternative for it, that would be welcomed info for consideration as well)

Extensions are allowed to do things, userscripts are not. However, in case of a preview a script should do fine. I do not know this extension, so I cannot tell for sure.
Even if I had it, I cannot do the conversion unless it explicitly allows to do so.

For now You can suppress signature checking in about:config
xpinstall.signatures.required;false
but this will only work until Mozilla removes this key.

This one has a more cumbersome display, but might be worth a try: https://addons.mozilla.org/firefox/addon/interclue/

@ gnblizz : thanks for making sure i was aware of that; i'm hoping for a more long lasting workaround i.e. a script

@ Scher: i almost mentioned interclue in my OP, guess i should've ;-) but thanks for making sure i knew of that option too. To me, it's more like a page inspection than a working preview (or mini-tab popup), where i'm hoping for the latter.

fwiw: tho i'd still luv to find a lay means to port an extension into a script, i just today discovered a Moz addon called Chrome Store Fixified that may pass as a workaround-- if the Chrome addon someone's told me about is similar enough to CoolPreviews... https://addons.mozilla.org/en-US/firefox/addon/chrome-store-foxified/