Testing the Get step in VStudio.bld (after changing the 'Handling of local writeable files' option on the Flags tab to Skip), it gets all read-only files and only skips writeable files. If your step is not doing that, compare it with ours (or check the 'Show command-line...' checkbox on the Options tab of the SourceSafe action, build the step again, and compare with the one in your batch file/script).
To ignore exit code 100, either mark the step to continue on failure (this doesn't affect the behavior the ss.exe itself--see above), or use the following VBScript code in the step's vbld_StepDone script event:
Code:
If Step.BuildStatus = vbldStepStatFailed And _
InStr(vbld_AllMacros()("LASTSTEP_OUTPUT"), "Process completed with exit code 100" & vbCrLf) > 0 Then
Step.BuildStatus = vbldStepStatSucceeded
End If
http://www.visualbuild.com/Manual/scriptevents.htm