I noticed the free space on my SSD was getting smaller. Searching for ways to clean up a bit I discovered a ± 10 Gb hidden folder under c:\users\(account)\appdata\local\(guid). Inspecting its contents, it turned out to belong to the RAD Studio XE6 installer. No need to delete them, but I didn’t want them to take up precious space on my speedy SSD, the files are very infrequently (if ever) accessed and could easily rest on my slower but larger regular harddisk.

So I moved all files to a new folder on the HDD drive under D:\Installer files\Delphi XE6 using Windows Explorer.
When it was done, I opened a command prompt in c:\users\(account)\appdata\local. Then typed this:

mklink /j "{0DE47792-19BD-4AF4-B9CF-6378FBA44825}" "D:\Installer Files\Delphi XE6\{0DE47792-19BD-4AF4-B9CF-6378FBA44825}"

(The actual guid may or may not differ on your system.) This creates a so-called junction point on the original location. No need to go into the details, but think of it as a shortcut-link-on-steroids. Now, the RAD Studio installer won’t know any better than that the files are still where it expects them to be, should you ever need them. It’s just on another disk.

(Disclaimer: use this tip on your own risk.)

Ad. 02-06-2014: another great way to free up some space on your SSD is by moving the Windows Installer package cache to a secondary HDD. The article under the link takes it one step further by moving it into a VHD to make future moves easier. I had to modify it slightly, because the security descriptor that is mentioned was not valid on my system. Tip: you can get the descriptor by executing

cacls "%ProgramData%\Package Cache" /s

on the commandline.

All in all, it is not a straightforward operation but may be worth it, since it consumes 2 Gb on my system.