The only thing you will need to do this is any Macro software. There’s loads of different free Macro software so use whichever you prefer. (I still haven’t settled on one yet)
First off choose the 10 keys you want for the 2nd bar.
Open your chosen Macro software and for each of the 10 keys assign the following macro:- Press Y, release Y, press [1-10 as required], release [1-10 as required], Press Y, release Y.This means that when you press one of your newly selected hotkeys, the macro software will swap to the 2nd bar [Press / Release Y], activate whichever of the 10 hotkeys selected [press / release 1-10] and swap back to your 1st bar [press / release Y] all on pressing one single key once.
If you find that the bar changes visually, but the required skill isn’t activated, then you might need to add a fraction of a second delay between the bar being changed and the required hotkey being selected, in this case your macro will be similar to this Press Y, release Y, wait 0.5 [will give half a second delay], press [1-10 as required], release [1-10 as required], Press Y, release Y.
N.B. Depending on your macro software will depend on the exact phrasing, some use press and release, others use key down and key up and others will only require the key without the Release or Up, please check your Macro software for exact terminology.