Using WAFO to estimate Tp associated with 100-year Hs

[ke]

I am looking to use WAFO to estimate the wave period (Tp) associated with a 100-year estimate of significant wave height (Hs), given a long time series of Hs and Tp. I would like to follow 'Joint modelling of wave spectral parameters for extreme sea states' (Johnson et al. 2010) which suggests the method below. I am new to extreme value analysis and so wanted to check if there is existing code or a WAFO example that could get me started. If not I will post back what I come up with.