Automatic detection is wonderful. Maybe the autodetected values could set defaults in mainsite parameters, so that if auto-detect fails, values can still be changed (and overriden) conveniently? Maybe this is how its done in 5.0 packages?
The wish is inspired from ecommerce pkg v4.6.1, where ispell is hardcoded at ../packages/ecommerce/www/admin/tools/webspell
