First, install wine in order to run win32 applications:
# sudo pacman -S wine wine_gecko lib32-mpg123 lib32-libxml2 lib32-openal lib32-libpng
You will also need this package from the [multilib] repository:
# sudo pacman -S lib32-libldap
Once the packages are installed, as a regular user run winecfg (win32)
# WINEARCH=win32 winecfg
# wine SugarSyncSetup.exe
Follow the instructions while keeping the default options. When done, uncheck the box "Run SugarSync" and click finish.
Running the file manager
After installation, you should find the SugarSync icon on your desktop or in the start-up menu. They are just links that invoke the following command:
# env WINEPREFIX=$HOME"/.wine" wine C:\\windows\\command\\start.exe /Unix $HOME/.wine/dosdevices/c:/users/Public/Desktop/SugarSync\ Manager.lnk
If the installation went right, the "SugarSync Login" window just show. If not, look if you followed the installation instructions correctly.
Quick start guide
Follow the Windows instructions in the official Quick start guide.
An update window poped up
In the case where an update window pops up, you can accept or cancel the installation, as you wish. There is nothing more to do than waiting for the download and update to finish.