There's not a definitive standard, but there are various conventions.
One option is to include two time signatures: the "actual" time signature and, parenthetically, the "compound" version expressing the metrical divisions.
Another option would be to include, say, a dotted barline to help visually divide the measure.
As the previous two examples make clear, the notation itself can make clear the intended metric divisions. Baring eighth-notes in groups of four rather than three, or use of quarter notes rather than dotted quarters, signals strongly the intended interpretation, even in the absence of a "fancy" time signature.
And finally, if needed, you can add accents to really make clear where the metric stresses should be.
