There is a way, and I have searched google and hit a few activeX controls that claim to do it.... however, I think you may have to go down to the lowest possible level... and here is the RFC for that: http://www.faqs.org/rfcs/rfc2251.html
The connection string.... I don't know. You'd have to read the RFC and figure it out... it seems fairly complex, however, requiring envelopes and other types of protocol standards.
A Multiple Column Combobox.... I have never seen what, but I'm sure you could use Tab spaces to make the appearance of one. I'll keep researching it... but it doesn't look promising.