PAL v1.x cannot do custom data points.
What are you using to measure the response times of an operation? Disk I/O has Avg Disk Sec/Read which is effectively the response times of the disk.
PAL v2.0 has the ability to create new counters based on other counters and apply your own formula to it, but it must have at least one real counter as an initial data source.
If you are talking about data that you create yourself, then I recommend just creating the chart yourself using the Microsoft Chart Controls via .NET. PAL v2.0 is using the MS Chart controls to create it's charts and it's a free object model.
Microsoft Chart Controls for Microsoft .NET Framework 3.5
If you want to create line charts using PowerShell, then let me know. I have a sample PowerShell function that I initially wrote for PAL v2.0.