postscript fonts vs. pango aliases

["Adrian E. Feiguin" <afeiguin uci edu>]

I am developing an application that is wysiwyg and generates postscript 
output. I have wrappers that basically assign a pango alias to each of 
the 35 default Adobe fonts, eg:
{
  "Times-Roman", // ps name
 "times, Medium" //pango name"
}

I want the output in the screen to look the closest possible to the ps 
output. The problem is that the user can change the fonts aliases at 
will, either with pangox.aliases or fonts.conf/local.conf, and make say 
"Helvetica" look like "Courier". I don't want this to happen, I want 
Times to look like Times, and Helvetica to look like Helvetica (unless 
the font is not present, in case I use "sans"). Any idea how to overcome 
this?

Thank you!
<ADRIAN>