short answer: no. Tk uses "core" X font rendering, which is not antialiased.
longer answer: the CVS version of Tk, which will become tk8.5, has support for
antialiased fonts on X. However, the CVS versions of Tcl and Tk were a bit too
experimental for general use the last time I looked at them. (in fact, a new
multiple-precision math library had just been added to tcl, and I couldn't even
get it to build---that was sometime this past summer)