There is a call to the ps2000SetSigGenBuiltIn function the PS2000.vi file so you can call the in built signal generator to output sine waves etc.
If you need the arbitrary waveform generator, then you will need to add a 'Call Library Function Node' block to your vi and configure it according to the function definition in the Programmer's Guide.
To generate a signal, you would have to capture the data, process it, making sure that it does not exceed 4096 samples, and then output using the arbitrary waveform generator. You would have to verify if that number of samples is sufficient for your application.
I hope this helps.