A classic clinical gamma camera was reverse engineered and retrofitted for the use of time dependent waveform maximum-likelihood techniques for the task of gamma-ray event parameter estimation. The original detector electronics were outfitted with tap-in circuit boards that intercept the photomultiplier tube (PMT) signals. These amplifiers send the temporal PMT voltage signal to off-camera 12-bit waveform digitizers. To include the temporal waveform data into the maximum-likelihood estimation of gamma-ray event parameters, waveform Mean Detector Response Functions (MDRF) are necessary. The collection of this MDRF differs substantially from conventional MDRFs because additional high-speed acquisition electronics must be used. The MDRF calibration requires 3 main processing steps which are done with a conventional MDRF: a spectral filter; a smoothing/fitting step; and a position-estimation filter. The waveform MDRF information can then be extracted from this result by tracking which events are filtered out from the dataset.