Memory-limited export to RSS feed

I’m experimenting with some alternate CMS systems, partly for fun, partly for… well, okay, JUST for fun. Anyway, I want to get my whole weblog into the new one, but it does not have a wordpress import plugin yet. As such, I wanted to do an export to rss2, which it does support, and then import that.

The problem is, my web host does not allow me enough memory to succeed at this directly. I get an error “Allowed memory size of 41943040 bytes exhausted (tried to allocate 352203 bytes)” when I attempt to create an RSS feed with my whole blog in it. I don’t really have access to the controls on this host, so this memory limit is, as far as I’m able to determine, immutable.

I tried forcing php to flush its output buffers after each entry, but that was not sufficient to save me, I still get the error beyond a certain number of entries. Things that I’ve read here and there on the net suggest that it might be WP loading the entire resultset into memory at once, which is too much for the PHP memory limit. Is there a way to force the backend to load entries in smaller chunks so that it can work with this memory limitation? I have about 320 entries, so it’s not a small chunk of text.

Thanks!