>I want to use OCX wich will establish connection to ACAD2000. Is there way to pass as a parameter file name I want to be open? Is there a way to trough OCX open a file as a read only?

You'll have to read the documentation for whatever tool you find that does this - I suspect that it will be something along the lines of automating Word or Excel, with it's own automation model, and lokking at the docs is about the only way to do this; there's no generic mehcnaism common to all automation servers.