Make this simple.

Throat of the World portal is now functional portal to Sovngarde. Just step in and woooooooooosh - you are in Sovngarde. Same for Skyrim. Use small light portal when you are in Sovngarde to return to Skyrim.

No complicated scripts or bugs...

Use this mod only after finishing main story quest!

How to install:

Just pud "SVPortal by Mika999.esp" file from rar into your Skyrim/Data folder

Enjoy!