submitting to openmicroblogging service (identi.ca)

as suggested by millette, the module is able to submit to laconica based openmicroblogging sites.

do the following:

cd /var/www/site/your.net/sites/all/modules/twitter
sed -i.bak 's/twitter.com/identi.ca\/api/' *.*

Now, the point is, that the url of the service shouldn't be hardcoded, but let users choose which service to use. how can this be achieved?
I'm a php beginner, so I would be thankful if anyone's willing to implement this. ;-)