I'm not aware of any plain command-line utility that offers the functionality of mIRC's /dde command. I'm not a programmer either, so I can't help you write one. However, I have two links that may interest you.
If you're a VB programmer, check this post
which will show you how to use DDE in VB. Otherwise, try my mIRC Batch
script, which registers the .MIRC extension with Windows for use as a mIRC batch file.
To use my script, load it and type /mf on
. This will enable you to execute any .MIRC file by double-clicking it, entering its name in the Start > Run dialog or launching it from a Windows batch file (.BAT) with the command START "file.mirc"
. The file itself should be nothing more than a series of mIRC commands, each on a separate line. (Tested on Windows 98.)