See this. If you aren't comfortable with the command line, the author of a free program called Find Any File lists instructions for using his utility to accomplish the same thing in a reply to the above linked post a bit further down the page.
In addition to following the directions from /u/JiggyWig, make sure you search your application support folders and preset folders as well.
I'd suggest downloading Find Any File and searching for "camel" and "alchemy" to see all of the different possible traces where this VST may have been installed on your computer. (Find Any File will search hidden and system folders by default, unlike Spotlight.)
Another alternative is Find Any File, but he's never quite tuned it to the level he needs to in order to make the thing my goto Find replacement. He's close though… I do have a hotkey to it.
I haven't find anything that does it automatically, but check out Find Any File (donation-ware) or iFileX.
Using these you can search using keywords and dates (e.g. the date you installed it).
Ideally I would love to have an app that would do a scan before-and-after I install the app and compare the changes.