I know you can do it straight through the dsp to the laptop, but I am not sure how.
Here is what I do to datalog to your tool then download to your computer:
First you need to download DS Dataviewer software
HERE
You will also need the PC interface stuff, which is a Serial to USB cable and a power cable for the DSP like
THIS
When you are ready to datalog, plug in your DSP to the OBDII port.
Select Diagnostics
Select Real Time data (I think you select real time streaming if going directly to a laptop)
Select watch and record
Go through and select the PIDs you want to log.
http://www.diablosport.com/index.php?name=PNphpBB2&file=viewtopic&t=21253 are some to get you started. The most common ones are RPM, MPH, ST KR, LT KR. If you have someone custom tuning your rid, do the PIDs they want you to do.
Scroll down and select watch and record
YOU ARE NOW DATALOGGING
Pres the esc putton to end
Then to download the log to your Computer:
Plug in the serial/usb to the DSP and computer.
Plug in the power cord to the DSP
Open DS Dataviewer software
Wait for it to "SEE" your DSP
Find the download log from tool icon, click on it
Once download is complete, click on the PIDs you want to display on the screen.
Mess the the setting to your liking. You can view as gauges, charts, graphs.
I may have missed a step, I am trying to go off memory since I am lazy right now and don't feel like walking to my truck and hooking everything up to take pics and write down every step. Give it a try and let me know if you have any questions