hehehehehe…. Last night I tried to put some liqueur in but still no change in the texture. So I simply put this in the fridge and going to put the buttercream in my cake. 
Now I am using another kind of buttercream, the cone is too soft, so I got this idea to put it in the fridge. After piping two cones, I put them in fridge with the piping bag. After a few mintues , I pipe the rose and remove the rose into the container. BUT…. the soft flower got smash after my careless transfer…. :( So after piping the rose, I fridge the whole rose on the flower nail and when it become hard, I transfer the rose with wax paper into the container.
BINGO!!!! I did it!!! Same here… my fridge will be open and close on and off…. hahahahah…. I will have to try this method on mousseline buttercream some day! 
Thank you LittleIsland for your input! Maybe some day we can catch up on cakes making and decorating!!!
Hope you can bear with me as I am just a very new beginner with cakes.
Cheers!