I hope this is helpful and not redundant info, however, in the mediabay of HALion, in the top right corner, there is an icon, where if hovered over with the mouse cursor, will show up as ‘show program structure’. This will list all samples contained within that VSTPreset. You can select any of these samples and drag and drop them into a slot in HALion and it will load just like any other sample/preset. This is great for selecting a single sample from a program, that would otherwise contain more than you were after. It works quite well too. The downside? Well you can’t audition what is contained within the programs, not until it is already loaded into a slot. Boo I know! This is a long requested feature, to be able to preview, in some manner, the VSTpresets in real time before they are loaded, but as of now, it is not possible. You will have to drag and drop the samples and play them from the slot to hear them, or if you know exactly what you are after, then that is even better.
See my attached screenshot where I have a VSTpreset selected in the mediabay, with the show program structure icon being clicked to list what is contained within that preset. I have then selected a single sample from the list and dragged and dropped it into a slot to use.