Invoker skills are added to him in different way, so you don't know which skill will be 5th or 6th in the template, so it can't be solved by customkeys.txt.
Rubick skills in theory we can make special customkeys, where his skills will be on qwer (for example) and everything else on D/F. However you will need always to replace special rubick customkeys.txt before map loads. So if there will be mode -ar/-sd/-rd/-cm and you need to play rubick it will be frustrating.
As we can't make customkeys for it we can make a tool which mouse clicks needed area, for example AucT Hotkeys Tool (AHT).
We can even use AHT whithout customkeys.txt to play some other map/Dota LoD etc. But there is small delay which not that good. So I came to conclusion to use both AucT Hotkeys Tool (AHT) and Customkeys.txt