Yeah those are probably the best way to request something.. You can always just post a plain text request to the corresponding group the material would normally be found in. However many of those groups have insane volume, and seldom are they 'watched' for request.. ie a.b.boneless
Some of the more specific requests, such as technical reading material, ebooks and such, are regularly requested for with plain text posts in the appropriate groups.. ie. a.b.e-book.technical