Occult for Non-Thaumaturges

Is it possible to use Occult to learn Thaumaturgy or thaum rituals without a teacher?

You mean the influence right?

Yes, the Influence, to unearth a Basic/Intermediate/Advanced ritual.

I think the general book concensus is that it take years to decades to learn without help, however I would be interested in the STs decision as well.

Starting at level 3 and above it is possible to research rituals. This can be read two ways,

Way 1, you walk into a room see bloody runes scrawled on the walls and candles that have been burned out, you know a ritual was cast here, you decide to research it and find out someone attempted to summon a demon. You don't have the power to do it yourself, but you know what the ritual is and how it's done.

Way 2, You walk into the same room hours before, you've spent months trying to perfect a "simple" summoning ritual, looking for the right components without bringing the attention of the church, and finally you set to cast, it works you've summoned the The Killer Rabbit of Caerbannog.

I'm going to allow people to study rituals and have the possibility of casting them, this will not be an easy task, and there will be failures, and it may draw the attention of hunters and church. Magic is dangerous, even more so when the first reaction of every good citizen of christiandom is to burn the witch.

A side note, rules for creating rituals will be posted later.

Remember that one must have prerequisite level of thuamaturgy (necromancy, koldunism, whatever) to be able to cast a ritual. The influence allows research of ritual, which makes sense for the first option you present, but there is nothing in the influence that lets you learn the actual powers of blood magic. Also keep in mind that at least under certain readings of the rules you must undergo a painful and invasive ritual before you can even use blood magic in the first place.

That being said, magic is cool and Occult 4 and 5 are kind pointless without being able to use magic. Maybe some compromise would make sense, as long as game balance is considered.