It most likely can be done but will take alot of work and knowledge. If you don't have any construction knowledge like stated i would suggest hiring an engineer to tell you how to do this. Another thing you need to check is the size, spacing, and length of the attic floor joists to make sure theycan support all this weight. If this was my house, depending on span i would like 2x10's for floor joists and then you could build a knee wall to support the truss webbing you are removing. You are going to be adding alot of weight up there and this isn't something you just want to guess on and hope it will support everything.