Songs for GH:WT (including DLC) was playable in GH5 (and presumable GH:WOR) using the free content update, I would try to find it in xboxlive marketplace rather than the in game music store.

with the death of guitar hero with no more DLC coming out after april, I would suggest you spend your cash on Rock Band DLC which pwns GH DLC, which is by default compatible between titles RB1-3.