[XeTeX] Beginner's question - font for numbers

[George]

Hello - is there a way to use a different font just for numbers, in a
non-math text? I searched the archives, but I cannot find anything....


Motivation: I am trying to write in Greek, using the "Times Ten Greek"
font, which does not contain oldstyle numbers. These come with the
"Times 10 Roman Small Caps  and Oldstyle  Figures", which does not
support  Greek.  Is there a way to "borrow" the number glyphs from the
latter [i.e., something like the SmallCapsFont={...} feature in
fontspec]? Unfortunately, non-english speakers face similar problems
often - they suddenly realize that small caps are absent from certain
scripts, usually after the purchase....