I'm trying to understand how to generate MC events for SUSY models at specific parameter points. To be specific: I'd like to generate squark pair production : pp $\rightarrow \tilde{q} \bar{\tilde{q}} (\tilde{q} \rightarrow \chi_0 qq \bar{q})$.
The general method seems to be to use the toolchain SARAH-SPheno-MADGRAPH to first get the SUSY-modelfile, generate the spectrum and then generate the MC-events. SPheno takes as input (depending on breaking mechanism) values for $M_0, M_{1/2}, sign(\mu), A_0$ and calculates and runs all other parameters in such a way as to satisfy the boundary condition, that all SM-parameters obtain the known SM-values.
But how does one specify the low energy parameter point popping up in an analysis? If I want for example $m(\tilde{q})$=500GeV and $m(\tilde{\chi_0})$=20GeV I can't just set them in the SPheno output file, since all other parameter should depend on them.