Currently, directly calling an onchain module without its source code isn't feasible. One approach is to use a remote or local dependency. You need to get the source code of the required module—a task that some explorers can help with using a decompiler, although it may not always be 100% accurate. Once you have the source code, copy it locally so that your package can reference it. For more details, you can look into the dependencies section of the Move book here.