Icelandic character composition not working

[Jay Smith]

Hi,

Sorry if this is the wrong list; I am not sure where to turn.

In RedHat Linux running under xwindows provided by Cygwin/XFree86, I am 
able to type all the "foreign characters" I need to use, except for one 
Icelandic characters (I can type other Icelandic characters).  Again, this 
is to type such characters in linux programs and documents running under X.

My "guru" mapped the Right Alt key as the Multi_key and so with it I can 
make characters like þ and Þ and Ä, etc., by typing combinations of 
letters, etc.

However, I have not been able to figure out how to make the "thorn" (eth) 
character which I think is 208 and 240 decimal.  It is the character that 
looks like a d or D with a horizontal line through it.

The docs say that I am supposed to be able to use:

   minus D    or      D minus

   minus d    or      d minus

(minus = dash = - )

I have Googled and just am not finding the right page.

Any ideas?

Thanks.

Jay