Is there any software that will compute cohomology of vector bundles (or just line bundles) on flag manifolds?

The only one I know of is Macaulay2, via the Schubert2 package, but it works with what it calls "abstract varieties", which are really just the intersection rings over $\mathbb{Q}$, so it's explicitly limited to characteristic zero. I'm interested in (among other things) bad behavior at small prime characteristics.