As abrsh01 points out, integration with SCM tools is not provided directly within DevTest.
The most common approach is to use the SCM tool to check out to the file system, use DT Workstation to maintain the assets, use the SCM's integration with the file system to check the changes back in.
It seems an Idea is planned for this (LISA Workstation Integration with Version control tool ). One issue I can envisage is 'which version control software does / should DevTest integrate with?'.