No, there isn't swap support for the Milestone. Swap support on the Linux kernel can only be builtin directly on the kernel, not as a module, and since the MS kernel is locked, we can't build and flash our own kernel with swap support.
So yes, the only solution is trying to hack swap support as a module, but since swap support wasn't meant to be used as a module in the first place, that would be quite a feat, sort of like jamming a square peg in a round hole - a doable, but very complex job, much more so than the dsifix (that's a walk in the park compared to swap module). It's also a not too rewarding one to the Linux community in general because the resulting work would only be usable with the specific Milestone kernel. And there are those that believe that swap support on the Milestone wouldn't improve things a lot - it could actually make things worse, it would probably require a very high performance microSD card to not get any slowdowns at all (nevermind getting speedups). That's one of the points that discourages development a bit, because the benefits of developing a swap module are dubious at this point, compared to the huge amount of work that would be required.
There were a few guys (2 or 3, don't remember) in the milestone dev channel that stated that they "were going to look into it", but they haven't been heard from in a while and those of them that have been heard from, haven't mentioned anything about swap module development since, so it's safe to assume it's not being worked on at all.
And rest assured, if there was a swap module already, it would trickle down to the ROMs available here pretty quickly, so the assumption that there could be some ROM for the MS using swap while others aren't is kind of silly :P