You could use the linear sweep voltammetry (LSV) test in the cheapstat firmware to do anodic stripping voltammetry. The settling time parameter can be used to set the time for your preconcentration step.
There is also a squarewave voltammetry (SWV) test in the firmware. This would almost do what you want for squarewave anodic stripping voltammetry. Unfortunately there doesn't seem to any period at the beginning of the trial which could be used for your preconcentration step. However, I think it would be pretty easy to modify the firmware to add this. The SWV test in implemented in the SWV_test function in cheapstat.c. For an example of how this delay at the start of the trial could be implemented you could look at the LSV_test function which implements the linear sweep voltammetry.