blackcoin-qt.exe -loadblock=C:\temp\bootstrap.dat

If you ever want to add in a command like that, its probably easiest via a shortcut.   The very first line you can just add -loadblock onto the end of the text and it'll use it when you double click next
To create a shortcut to anything right click and it's on the menu create shortcut.   Then you can drag and drop your icon for shortcut to desktop or anywhere.   Then you right click shortcut > properties to edit, its the first line as I said above.

Other commands are listed near the help menu once loaded.   -rescan is one sometimes helps
-reindex I think was mentioned recently
-datadir=
That one is for when you want blackcoin to look for its files in a new directory, like C:\temp I gave as an example above.     

You can always just create a new folder to put files in, no rules against it.   I dont believe blackcoin is bound to any awkward directory or just the C drive.  Just tell blackcoin where that folder is with -datadir, use your own name for the folder; temp is just my example and I'll be in trouble recommending that :p
Same thing again, right click New>  folder and rename to anything