I would say yes, since "spellcasting class" is what is needed to advance in invocation power when taking prestige classes, which Warlocks can do. But Practiced spellcaster would not give the warlock more invocations, but just make the invocations she has of a higher level (most relevant to damage by Eldritch Blast, I would assume).
I think a rogue with 1 or 2 levels in Warlock would be pretty good. Nice to have a 1d6 ranged attack that you can sneak with (on a surprise round). But I am not so sure about high level warlock with a level or two in other classes. It just it too tempting to continue in the warlock class and get that next invocation.
Maybe some sort of "mystic theurge" version of a warlock, or "Arcane trickster" or "Eldritch Knight"? I don't think as written those prestige classes could do it, but it would be trivial to make close cousins of those prestige classes.