Depends on the Packer/Crypter you wanna intercept.
If there is not much poly decryption i would suggest to code some basic r3 Loader that sets some small Breakpoints,...

If too much junk and poly i would suggest to hook an Api-Function near the Place you wanna intercept..

I think i saw you posting on an other Forum aswell.. If you want to do an Asprotect Patcher/Loader (I think i remind that from the Forum i saw u posting), I can tell you Global and me did our Asload just with Ring3 Routines (Read/Write ProcessMemory etc.) and some scanning ofcourse,but no Apihook needed at all.