Styler 6.0 added a Side by Side tab. Honestly, I'm not sure how to use it in the context of a list's item number/label. Mine are all upgraded FOSI source edit algroups (the FOSI side by side Gareth mentioned).
I would try to create a User Formatting Element, wrap the gentext element with it, and format the UFE using the Side by Side tab.
Also, if you haven't solved this or moved on already, is to join the Adepters mailing list where lots and lots of Arbortext users, admins, and developers hang out 24/7/365. Information on joining that list (as well as pointers to lots of other Arbortext resources) can be found here:
http://blog.single-sourcing.com/top-arbortext-resources
See also:
http://www.single-sourcing.com/company/social.html
Good luck!