I found this video while searching YouTube for tutorials on putting together Rhinos, Vindicators, and Land Raiders (oh, my!). In a nutshell, the guy (who goes by the handle AwesomePaintjob) in the video suggests using colored pencils for hard lining the edges of vehicles as an alternative to using paint brushes. The result seems pretty good and as the guy says in the video (paraphrasing): "While some of us may be unused to doing detail work with a paint brush, we've all used pencils before."
Remember, the poll from Post 31 is still active, so please vote if you haven't already. Thanks!