How do I get MarvinSketch to use the ACS style of drawing?
You can find some information on JACS style here.

If you are using Marvin Sketch 5.1, first clean your structure, then got to edit then format. Click the Apply changes for all the atoms / bonds and then Load Style. Pick J. Am. Chem. Soc and OK.

In Marvin Sketch 6 open File then Document Style and continue as above

For more information see the documentation here.

That should work