filenames with the commands
<texcode>\usetypescript [adobekb][\defaultencoding]</texcode>
or whatever encoding you want to use. After that you can setup yourfont with
<texcode>\setupbodyfont[pos]</texcode>
and similar commands.
Added on July 5th, 2005 (by Otared K.):
After some of us had difficulties using Postscript fonts, it seems that as of ConTeXt version 2005.06.27 (and pdfeTeX, Version 3.141592-1.20a-2.2 (Web2C 7.5.3)) the following declarations are the appropriate way of using Postscript fonts (in this instance we say "“times", ” but you can say "“palatino"”):
<texcode>
</texcode>
Note that in the case of "“helvetica" ” the last two lines should be replaced with:
<texcode>
</texcode>
since "helvetica is sans serif.
Here is an example:
E.g. load the typescript ''palatino'' like this
<texcode>\usetypescript[palatino][\defaultencoding]</texcode>
and switch to palatino with <cmd>setupbodyfont</cmd>
<texcode>\setupbodyfont[palatino,12pt]</texcode>