"Make ready, O Jesus, to thee now the way,
My Saviour, elect now
My soul ever faithful
And look down with eyes full of grace now on me!"
given by Q is a pretty literal translation. "Itzo" is indeed an archaic, poetic form for "jetzt"=now. "Noch itzo" means "still now". I consider it a filler without any actual meaning, simply inserted to make the words fit the music.
"Bereite dir" means "prepare for yourself". In german reflexivity is seldom actually expressed, only when there might arise a misunderstanding. In English you shave ME but I shave MYSELF. In both cases I am the one who is shaved. If I said "I shave me" this would only be gramatically wrong but it would still be clear who is shaving and who is shaved. This is done in German: "Ich rasiere mich." I say "Ich rasiere mich selbst" when I want to stress that I am not assigning this task to anybody else, not when I simply want to say what I am doing. The issue here is not a matter of dative it's a matter of reflexivity.
There is a second way to understand "bereite dir". "Bereite" is not only imperative but also 1st person singular, present tense: "ich bereite dir" = I prepare for you, and as in English it is also possible to omit the "I" in German. However I consider this meaning less likely. Still it is a nice example for a reason to say "yourself" although in most cases "you" would also say what is meant: this would avoid the ambiguity.
There might also be a way to misunderstand the upper translation. What is said is definitely "for yourself" or "for you" (in case I was doing it), not "to you" in the sense of a way "to heaven" or "to New York".
As for the meaning of the first line I understand it as "Fight your way, Jesus", not the way to heaven but rather in general, whereever he is going, or even the way to me in particular. But I admit that it is not completely clear.
All the best