There is the command line (partially XML-based) interface to the Vault. I've been using it from VFP to obtain the latest versions of files.

cClientmodule="C:\Program Files\SourceGear\Vault Client\vault.exe"
. . .

cCmd = '"' + THIS.cClientmodule + '" GET' +;
	" -host " + THIS.host +;
	" -repository " + THIS.repository +;
	" -user " + THIS.user + " " +;
	" -password " + THIS.password +;
	' -destpath "' + m.cLocalPath + '"' +;
	" -setfiletime current" +;
	" -makewritable -merge overwrite " +;
	'"' + m.cSourceGearPath +'" '
	
THIS.ExecMsdosCommand(cCmd, "Retrieving files from SourceGear " +;
	m.cSourceGearPath + " to " + m.cLocalPath)

If there is a way to search through the history, it certainly should be mentioned and described in Vault developer's manual.