I've just posted the first version of VDLMidi - a freeware software input device for Mac OS X 10.4 ('Tiger'). It makes it easier to input percussion sounds without the need for a MIDI keyboard, by showing a list of the available sounds and allowing you to click them to input notes.
I hope you will find it useful for any work that you do with Virtual Drumline 2. I have tested it with Sibelius 4 (which is what I use), and I expect that it should work with Finale and other apps as well. Please let me know if you find things that do or do not work in other applications.
There are plenty of things left to do - such as adding the rest of the keymaps (it currently has snare, tenor, bass, cymbals, and a few others).
Jim has been very supportive in my efforts to make this happen, but it's not an official app from Tapspace, so please send any problems to me. (vdlmidi at gmail)