All tools need TMC and TMCL. In case of you only have TMC only, copy one of existing TMCL file(My recommend is Harry's RNM). Rname the TMCL as same as TMC(except extension, oc). Then Texture Tool can work as add/remove/replace texture files. Then you can assign which mesh will use which textures using TMC Object Tool. When you edit TMC file using these tools then they adjust TMCL accordingly.