If you are using TortoiseCVS (and have nothing else using overlay icons), you will get a couple of TortoiseSVN Icons, and all of your TortoiseCVS icons. This is because the overlay icons are used in alphabetical order. Again, at your own risk (editing the registry may blow up your computer, yada, yada, yada -- and if you are reading Stack Overflow and using Windows and haven't edited the registry, you are a rare beast indeed), feel free to rename them (I suggest putting numbers in front of the ones you want to use and "z_"'s prefixed to the ones you don't need). The TortoiseSVN Shell extensions are nicely named so you know what they do, the TortoiseCVS extensions are not. After looking through the source code, I found the pertinent information:
rem Set your own path.
set TOOL_ROOT=d:\Tools\TortoiseSVN-1.6.13.20954-win32-svn-1.6.16\tortoisesvn_1.6.16.21511
set PACKAGENAME=TortoiseSVN-1.6.16.21511-x64-svn-1.6.17.msi
set TOOL_INSTALLROOT="c:\Program Files (x86)\TortoiseSVN"
msiexec /i "%TOOL_ROOT%\%PACKAGENAME%" INSTALLDIR=%TOOL_INSTALLROOT% ALLUSERS=1 ARPSYSTEMCOMPONENT=1 RebootYesNo=No REBOOT=ReallySupress /qb-
set ret=%ERRORLEVEL%
rem The installer seems to return same values as MSI
rem These codes mean that the product is properly installed, even though the code is not zero.
rem 1641 ERROR_SUCCESS_REBOOT_INITIATED
rem 3010 ERROR_SUCCESS_REBOOT_REQUIRED
if %ret% EQU 1641 set ret=0
if %ret% EQU 3010 set ret=0
if %ret% GTR 0 exit %ret%