[imp] searching idea for external access to horde/imp

[Karsten Römke]

Hello!
I'm using two "web-programs": horde and a self written
"infosystem". Both use the same ldap server to authorize
the user.
Now I want to use the infosystem to open an imp window
to compose a mail to some people wich I get from my
"infosystem". I have the following problems:
1.) howto access imp/compose.php and submit the information
    that the user is logged on / submit username and password?
2.) how can I set the To: field in the compose window?

Any hints would be nice

        Karsten