There are plenty of talented modders (Helioforge is one of them) around these forums who can help you if you run into trouble. However, you should try it first for yourself to get a feel for making abilities and to try and figure it out.
More people will be willing to help you solve a specific problem rather than walking you step by step through making the entire ability

I don't think the tutorial PDF goes too much in depth about ability scripting, so the best advice I can give you is to look at existing similar ones. For example, you can look at the Progenitor Mothership's shield recharge ability, so you can see how shield recharge modifiers are done.
Bailknight put together an awesome list of all the various modifiers ability scripting uses
here. It seems daunting at first, and will be until you look through and figure out the flow of logic in the ability files and play around a little

And I can help pitch in with the basics, but as I've said I haven't created this type of an ability so beyond the basics of "how everything works" I won't be able to tell you much that you can't try yourself