When you install TortoiseSVN you are given the option to install the Subversion binaries as well:
Once you do that, you will see svnsync.exe
in the installation folder:
As long as you have C:\Program Files\TortoiseSVN\bin
in your PATH
variable, you will be able to call svnsync.exe
from the command-line:
(You can view your PATH variable thus (on Windows 7): Start ->
right-click Computer ->
Properties ->
Advanced system settings ->
Environment variables.... DO NOT overwrite whatever is there - simply append the path to TortoiseSVN if it isn't already there. More info here.)
Hope this helps.