I think your best bet is to create it as a source. Adaway can only compile sources and lists and has no capacity to discern addressesThanks.. I'm not trying to block these IPs. What I'm trying to do is override DNS so that lookups for youtube.com always return 18.104.22.168 and not one of the alternate IPs.
[I have separate IP tables rules which block all Google/youtube netblocks with the exception of these two IPs]