An inexpensive midi controller will make the job of inputting the midi notes so much easier.
Some music stores may allow you to return the software..... but that will depend on their policy. Generally it is UNOPENED software. Once you open it, to get it to work past demo mode, you have to register and unlock most of them..... once that is done, no one else can unlock it so they rarely allow returns on opened software.
Using the mouse is a slow way of inputting the notes, but it is not impossible to create some very nice compositions in this manner.... although it does take time.
Don't forget.... if you have MC5 or 6... you have LOOPS. Both midi and audio if I understand correctly. Using loops, and there are lots of different loops in there, you can create a song in only a few minutes by dragging the song part loops together in a project. There is a video on the page link I posted above that shows that very thing.
This is a fun little project I did using loops in MC6/X1essentials to create a song....
http://soundclick.com/share.cfm?id=11450431 It is totally loops, no live playing in this at all..... it was an experiment to see what I could do....and this was done in no more than 2 hours just playing around. I do not use loops in my music BUT... I decided to play with them one night just to see how they work....
Try the loops and see how you like them.