[XeTeX] Matching font scaling

[Pepe Romero]

Dear all,
I wish to use the Poliphilus roman typeface with Blado italic.
This I can do easily thus:
\setromanfont[Mapping=tex-text,%
  Ligatures=Common,
  Numbers=OldStyle,%
  SmallCapsFeatures = {LetterSpace=10.0},%
  ItalicFont={Blado MT Std Italic}
  ]{Poliphilus MT Std}

However, I want to match the scale of the fonts, since Blado is smaller than
Poliphilus. I thought I could do something like this:

\setromanfont[Mapping=tex-text,%
  Ligatures=Common,
  Numbers=OldStyle,%
  SmallCapsFeatures = {LetterSpace=10.0},%
  ItalicFont=[Scale=MatchLowercase]{Blado MT Std Italic}
  ]{Poliphilus MT Std},

but XeLaTeX (fontspec) does not recognize that option.

Does anybody knows how this can be accomplished?

Thank you all,
Pepe Romero
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://tug.org/pipermail/xetex/attachments/20090126/704f18fb/attachment.html