Phrase/Word model creation from standard model

What are the steps to convert a regular model into one that can handle phrase_list

```
https://alphacephei.com/nsh/2020/03/27/lookahead.html
```
Can we just do this, and what is needed in data/lang?
```
am=/path/to/am/
export LD_LIBRARY_PATH=${KALDI_ROOT}/tools/openfst/lib/fst
utils/mkgraph_lookahead.sh --self-loop-scale 1.0 --remove-oov --compose-graph \
data/lang ${am} ${am}/graph_${lm}_lookahead
```