How to configure Keycloak Helm Chart
You can use kompose tool to directly convert docker compose to kubernetes files. If you want to make a helm chart just replace with templates and provide values in chart values. Also Kubernetes deployment has command field in yaml.
as you can see in github.com/codecentric/helm-charts/blob/master/charts/keycloak/… command is set by .Values.command
So in file github.com/codecentric/helm-charts/blob/master/charts/keycloak/… replace command : [] with your docker-compose command.