well this worked out for me, but i still dont know why registerserver=yes fails to embedd activex perfectly:: new inf file is as following::
[version]
signature="$CHICAGO$"
AdvancedINF=2.0
[Add.Code]
xyz.dll=xyz.dll
[Deployment]
InstallScope=user|machine
[Setup Hooks]
xcxc=xcxc
xcxc1=xcxc1
[xyz.dll]
file-win32-x86=thiscab
clsid={HJI9D4D39-K9F5-489B-8032-CCHB1B189J10}
FileVersion=13,0,0,0
RegisterServer=yes
RedirectToHKCU=yes
HRESULT IEInstallScope(LPDWORD pwdScope);
[regDll]
hook=xcxc
[xcxc]
run=C:\Windows\System32\regsvr32.exe "C:\xyz\13\plugins\ie\xyz.dll"
[abcDll]
hook=xcxc1
[xcxc1]
run=C:\Windows\syswow64\regsvr32.exe /u /s "C:\xyz\13\plugins\ie\xyz.dll"