32 bit system:

regsvr32 "%SystemRoot%\System32\actxprxy.dll"
regsvr32 "%ProgramFiles%\Internet Explorer\ieproxy.dll"

64 bit system:

regsvr32 "%WinDir%\SysWOW64\actxprxy.dll"
regsvr32 "%ProgramFiles(x86)%\Internet Explorer\ieproxy.dll"