So, I decided to take a fat chance and try installing Gallery 2.2 (Latest) with vBulletin 3.6.8, and lo and behold it worked. Well, almost.
Here's what I did:
I created the gallery2 directory within the forum home, as indicated.
But then I struck a small problem. The "Your album" as well as clicking on an image, would take me to /v/<name>.

So, I then proceeded to move gallery2.php to /gallery2/gallery2.php, (didn't need to change the embed.php line or anything) and nothing came up. I then linked the file back to gallery2.php and it worked.

No snags yet. (See minor issues below.)
I did try and add the .xml files for the two addons, and also hit a serious snag.:erm:
Trying to add it as a product said this looks like a Plugin...
Ok, so now to add a plugin.
And I had to do a quick crash course. So here goes for those that don't want to do too mouch soul or web searching:
In the add new plugin part:
- Select vBulletin in the first dropdown. (Mine contains vDrupal as well.)
- Select the Hook Location as userdata_postsave in the first one and userdata_delete in the second one.
- The titles are "Update Gallery User" and "Delete Gallery User" respectively.
- Now take the first section from "CDATA[" (Not including, in otherwords, first line starts with "require_once") up to before "]]></phpcode" and paste that as the Plugin PHP Code.
- Make sure you do this for both parts, that are listed within the xml file.
- Ensure that you have enabled the plugins, and you're done.
I am still trying to figure out, how to not pass the gallery out of the vBulletin forums, when you click on "My Gallery" and any images.
This however is not a major issue right now, as I will change the skin to allow you to go back to either the home page or the forum anyway.
Thankyou for all the work Brent. Well done.
Now I need to figure out how to do a group control from vBulletin to gallery, whereby only members of a specific forum group can add images to the gallery.