For adding a dll or ocx in vb6 via win7 u should search UAC in start menu then
click on Change user account setting , and in the opened window move tracker to Never notify , next click ok and restart computer. after that u can add any dll and ocx into system32 by regsvr32 command.
Notice: moving tracker to never notify can allow some inactive viruses and worms to be added into your registry.so after adding your own dll's or ocx's change windows security to it's default.
Enjoy life.
