Depends on the other program and how it accepts the data you're trying to "dump" - which one did you have in mind?
You can write VBA routines and can use COM objects to do a lot of different things, but be aware that Excel is fundamentally a spreadsheet program with scripting capabilities, it wasn't designed for extensive realtime functionality or to be used as a substitute for a data transfer gateway - so don't expect to be able to pump hundreds of symbols worth of tick data through it efficiently.
