Hi Kimberly,
An interesting question -- we have discussed developing an export filters to generate XML for desktop publishing applications, but not the other way around. In particular, our partner journal
Open Medicine is using Lemon8-XML to export XML for editing in
Scribus. Lemon8-XML is built around the
OpenDocument format, which means that any file type that can be converted to OpenDocument can be imported by Lemon8-XML.
In the case of Pagemaker, it should be possible to export the file as RTF, and then subsequently convert the RTF file to ODT (either manually or directly by Lemon8-XML, depending on how it's configured), which can then be processed normally. We've obviously never tried this path, but would be very interested to see how well it works, what issues it may entail, etc. We are aiming to release the public beta of Lemon8-XML near the end of the month, which will include the source code for you to try it yourself. Please stay tuned as we near the release!
Regards,
MJ