"I myself" is a perfectly good translation of καγω (I too; I also) in this verse.
This is because more literally, it translates:
And I have made your Name known to them, and shall yet make it known, that the love with which you have loved me might be in them: that I too might be in them.
In any case, Jesus knows that where the Love with which the Father loves the Son is, He also is. It is my opinion that this Love is nothing other than the Holy Spirit, and such indeed is traditional to believe. But not without reason. Take, for example, this passage:
John 14:15-18 (DRB) If you love me, keep my commandments. 16 And I will ask the Father, and he shall give you another Paraclete, that he may abide with you for ever. 17 The spirit of truth, whom the world cannot receive, because it seeth him not, nor knoweth him: but you shall know him; because he shall abide with you, and shall be in you. 18 I will not leave you orphans, I will come to you.
Jesus dwells with us via the indwelling of the Holy Spirit, whom He gives, together with the Father, and this is how:
...my Father will love him, and we will come to him, and will make our abode with him.
John 14:23 (DRB)
"In" or "among," either way the doctrine is the same. Technically it's ambiguous, however, things like "will make our abode with him" etc. seem to suggest a personal indwelling of the individual, not just a congregational presence (cf. Mt. 18:20).
Personal indwelling does not necessarily follow the belief of the individual.
Acts 2:38 (DRB) But Peter said to them: [Repent], and be baptized every one of you in the name of Jesus Christ, for the remission of your sins: and you shall receive the gift of the Holy Ghost.
This is Jesus' last highpriestly prayer while yet free to make such, and so He wants to leave the provision of the Holy Ghost, so as not to 'leave them orphans.'