According to Wikipedia, æ in Old English was pronounced something like the A in "cat", so this name would be pronounced something like AL-red (Al as in Albert). But then again, the name Æðelræd was modernized as Ethelred, not Athelrad, so maybe Ælred could be modernly pronounced EL-red ("el" as in "eldritch").If I could get away with it, I'd totally name a kid Ellred.
(Source: https://simple.m.wikipedia.org/wiki/Athelred_of_Wessex)
Maybe Alred or Elred could work as moderns forms?