I think the information quoted in tsastor's reply is for Domodedovo (DME), not for Sheremetyevo (SVO). I think the only chance to get into a lounge with a Y ticket is to have sufficient level in some FF program.

And having to wait for three hours in SVO really is the pits. Downstairs you can't sit, upstairs they have built all manners of refugee camps, so there is no alternative but the lounge (or the hideously expensive "cafe's").