There is a utility script pipe command in IOS-XR. the script option (like many things in IOS-XR it seems) is undocumented. Where is the proper location for scripts to live? it appears to want them in /misc/scratch (or /disk0:, which is the same thing...

How to pass an inline set to a parameterized policy? This doesn't appear to be possible, in spite of language (quoted below) implying that it should be. with this policy: route-policy lpref-communities($lpref, $communities_set) set local-preference ...