Dein amerikanischer Kollege hat völlig recht.

Begründung zu dude:

Die zentrale grundsätzliche Idee des Konzeptes des Reflexivpronomens ("myself") besteht darin, dass es auf eine im Satz zuvor genannte Person zurückverweist. (In den allermeisten Fällen ist diese Person das Subjekt; es gibt prinzipiell aber auch andere mögliche Konstellationen.)

In dem von Dir angegebenen Beispiel wirst Du selber ("myself") vorher nicht genannt. Damit scheidet das Reflexivpronomen als Option aus, und man muss ein normales Objektpronomen ("me") wählen.

@Londoner: I'm not sure I agree with your assessment. Even if the person had been named before, the "self" ouldn't be a necessity or even necessarily correct. You might use the "self" to emphasize the fact that, indeed, "I will do this myself" and with nobody else's help, as opposed to "John and I will do this."

“Myself” is no better than “I” as an object. “Myself” is not a sort of all-purpose intensive form of “me” or “I.” Use “myself” only when you have used “I” earlier in the same sentence:


http://www.wsu.edu:8001/~brians/errors/myself.html

@dude: I agree, of course, that "myself" can be used for emphasis, i.e. without fulfilling the genuine function of a reflexive pronoun.
However, my statement was about a NECESSARY condition that must hold when you would like to use a relative pronoun, namely that the person the pronoun refers to must have been mentioned before.
(What I did not say is that this is a SUFFICIENT condition in the sense that you can always use a reflexive pronoun when the person the pronoun refers to has already been mentioned.)
Do you know any example where the necessary condition is violated? (If so, I'll be surprised and happy to improve my concept of reflexive pronouns.)

Sorry, of course, it should have read "reflexive pronoun" instead of "relative pronoun" in the second line of my previous comment.

I agree that it's poor style and you're better off not to imitate it, but I'm not sure I agree that it's a particularly BE mistake. At least, there are plenty of Americans who make it; otherwise it wouldn't show up on Prof. Brian's (Brians's? never can remember that guy's name) list of common errors (#4).

Ich habe kürzlich mal eine sehr einfache Erklärung gehört, wie man überprüfen kann, ob das nun richtig ist oder nicht, wenn man nicht sicher ist, und zwar:
Aus dem Satz "This will be done by X and myself" die andere Person, also X, herausnehmen. Dann hört man meistens gleich, daß es ziemlich falsch klingt: "This will be done by myself" geht nicht, also ""This will be done by (X and) me."

Jetzt fällt mir auch wieder ein, wo ich das gehört habe, und zwar gibt's hier...
http://grammar.quickanddirtytips.com/
... einen richtig netten Englisch-Grammatik-Podcast (hoffe, das ist nicht zu viel Schleichwerbung hier... ;-) ). Da hatten die das in einer Sendung.

Right or wrong, many people do use "myself" this way. Here is a very recent example from a talk given by David Letterman:

Bad boy, David Letterman!