Old Soul....The first person pronoun is 'ly "to, toward me", not 't which is a direct object marker ('ty is an object pronoun) or preposition "with". The MT text is: w-bhytw "and they will look" 'ly "to me" 't 'shr-dqrw "whom/on account of whom || they pierced"; cf. the JPSB rendering, "They shall look unto me because they have thrust him through". The sense of 't 'shr as something other than "whom" appears in the LXX which uses anti "instead of, because of" to express the idea that the divine "me" and the one being pierced are separate persons: epiblepsontai pros me, anth' hón katórkhésanto "and they shall look to me, instead of || because of the one they have mocked" (katórkhésanto "they danced insultingly" occurs instead of the expected exekentésan "they pierced" because of a scribal error in the Hebrew between dqrw and rqdw). The Greek version of Aquila is also painfully literal of the Hebrew and also disambiguates the two persons: epiblepsontai pros me, sun hó exekentésan "they shall look towards me, with the one whom they pierced". The context strongly favors the disidentification of the divine "me" and the pierced one because of the pronoun shift in the rest of the verse: "They will look to me ('ly) on account of the one they have pierced, they will mourn for him (`lyw) as for an only son, and weep for him (`lyw) as people weep for a firstborn child" (Zechariah 12:10). The text is ambiguous as to whom the "they" and "him" refers to, but I believe the best sense can be gained from understanding the "they" as the "clans of Judah" (cf. v. 10: "they will mourn for him", v. 12 "the country will mourn clan by clan") and the "him" as referring to a generic "one they have pierced", which refers back to v. 6: "When that day comes I mean to make the clans of Judah like a brazier burning in a pile of wood, like a flaming torch to stubble; and they will consume the peoples round them right and left". This refers to the holy war between Judah and the Gentiles in the preceding verses ("All the nations of the earth will mass against her," v. 3). Contextually, the mourning is best understood as by the Jews for all those whom they had killed, mourning each dead person "as people weep for a firstborn child".
The text in John 19:37 (opsontai eis hón exekentésan "they will look to the one they have pierced") modifies the Zechariah passage in two important ways. First of all it interprets the 't 'shr as eis hón "(in)to whom" rather than sun hó "with whom" or anth' hón "instead of whom, because of whom" which distinguish the one being looked at from the one who was pierced. This rendering follows that of Theodotion rather closely: kai epiblepsontai pros me, eis hón exekentésan "and they will look towards me, to the one they have pierced". Here the translator has conflated the two persons. But the author of John takes this one step further by omitting the pros me, making the one being looked at explicitly the one being pierced. The application of this verse by John ignores all sorts of contextual facts as well. The ones who "pierced" Jesus in John are Gentile soldiers, whereas in Zechariah the people who killed the "pierced one(s)" are those from the clans of Judah. In Zechariah the "looking" and "mourning" occur at a time after an eschatological war between the Jews and the Gentiles (which not the case in John).
