you can leave LB on C and move all of the assets to your other drive but I'm not going to lie depending on how many systems you have it can be a pretty lot of work and you have to move each category per platform individually. To do so you just go to manage platforms edit the platform you want go to the folders tab and begin moving things to the folder you want. You can also do this by moving all the folders and then creating a symbolic link back to the original location this will have you assets on your data drive but LB will think they are in C the only issue with I believe is if you add new images they will actually be put in C and not on your data drive.