My name is David, I work at a Kenworth Dealership in Texas.
I'm going to try and attach a couple of CAN Start-up templates to help with Waveform captures for 250 KB and 500 kb CANS. I don't know if this will work.
If you message me from this forum I may be able to help you with some ideas concerning connecting to the 9 pin diag connector.
For those using the guided tests there is one for Serial Decoding. This will load similar settings to the ones David has created below. When using PS6 you will notice the decode table is automatically populated but is set to decode a 500 kbaud network. This can be easily changed to allow 250 kbaud by selecting the settings cog in the decode table.
There is the same guided test in the latest edition of PS7 but serial decoding is a feature not yet available.