It is a different usage. "To help oneself to something" is idiomatic "to help oneself into something" isn't and the two phases do not mean the same thing.Let's say a different preposition, not usage. Does it always imply without permission?
You are back to lack of context. For a possible context and meaning of 1) see the link given above by DerPilz. For 2) this isn't, for me, a usual phrase - although perhaps there is a context that hasn't occurred to me where it would work. I could make a guess at what it means depending on the context, as I do above where I assume "let himself in" is meant.Do you mean that each option has its own meaning?
1) To help oneself to something
2) to help oneself into something
What does each of them mean?
PS Well, at least the first one.
1) Took without permission.1) A bank employee helped himself to £12450 from the savings account of a retired couple.
2) Jesus helped Himself into this high state of being by His use of the spoken word.