There are some KB articles that demo how to use some tools to access Service Desk Rest API. For example
There are also some sample java scripts that demo the login and other API actions.
Is there a complete script that can take end users username/password and use that to receive access token and use the token for other actions? Something like a mini program written using SDM Rest API.
CA Service Desk 17.x
Currently there is no such script available from Broadcom.
Every platform/programing language has its own way to get user inputs and use the user inputs to call SDM Rest WS API to login, parse the return to get the access key and use the key for further actions. There is no generic "template" that you can use - every platform/programing language is different.
CA SDM provides the Rest WS API and how others consume and use the API is totally up to them.
Programmer would need to write the script to have user inputs and use the inputs to call Rest API to have an access token and then use the access token to query, update, create SDM objects. The script would be any programing language/platform that can consume the Rest API and writing this script is out of scope of support.
It is not practical to have such a "template" as it could be java, Visual Basic, C/C++/C#, Python, R etc. and it could be from a desktop, internet/web or even from other web services.