barometric compensation

When using alpha-n strategy it is important to set a barometric compensation table. How should this table be filled and checked on a dyno?

Typically I'd still include a MAP signal to the ECU. This is used as a background fuel calculation on the principle that double the manifold pressure requires double the fuel to maintain a consistent AFR. The MAP signal of course is also affected by barometric pressure and as such the fuelling will change as barometric pressure changes although relying on MAP alone almost certainly isn't going to give you perfect results. If you're expecting to encounter large changes in baro pressure then a baro sensor can be added and used as a compensation table. This really needs to be tuned at each baro pressure point though to ensure it's correct.