So it still may be more beneficial if you keep using only 8 materials per object at max (thus do the splitting into subobjects by yourself).
Anyways Avastar 1.6 will support the export of more than 8 materials per object. If you have an account on the Machinimatrix website, then you find the newest Avastar-1.6 Alpha release in the_archive subfolder of your download page. The exact name of the download file is:
Note: If you use the anonymous download page (without using an account on our website) then you have no access to Alpha versions of the software. But of course you always can create an account on our site to get full access to the archive folder.