Adriano,
The way to do this would be from the command line. First create a PDO (overlay) with an entry containing only memory tests say #8, 1 with only CPU #9 and one with only disk #10. Then create a batch file that calls then in the number and quantity you wish.
The user manual has a listing of the command line switches. PC-Doctor is very powerful and flexible from the command line but it takes some time to get the hang of it.
The following example is a simplebatch file to accomplish what you want. In it, /ba:xx is the .pdo file overlay number you want to run, /pc:xx is the pass count and /pr:xxx.xxx is the log file name. By default the logfile will append to the end of an existing file. You should always log to the ramdrive then copy it wherever you want.
rem custom.bat
pcdr /ba:8 /pc:3 /pr:test.log
pcdr /ba:9 /pc:10 /pr:test.log
pcdr /ba:10 /pc:1 /pr:d:\test.log
Happy scripting...
-Fred