[imp] spell checker - multiple choice

[Matjaz Kljun]

I seems that I dug the whole web to find the answer to this one. What I 
try to do is to
have user be able to choose in which language he wants to spell check 
the message.

I have horde 2.2.5 and imp 3.2.3 installed.

In the 'path_to_horde /horde/imp/confing/conf.php' I specified the 
Aspell as the spell
checker.

$conf['utils']['spellchecker'] = '/usr/local/bin/aspell';

It works fine in imp but only with the English language as default. I 
would like to choose
the language for check speller. I can do this in the command line

my server # aspell --lang=sloveninan --check test_sl.txt
my server # aspell --lang=english --check test_en.txt

but have no clue how to do this in the imp? And I know that it's 
possible since I saw it
on some imp installations on the web.

Thank you for the answer.