Interesting question. Theoretically this should not be a problem. However, since this is a totally elective procedure, even the most remote chance of an untoward event would compel me to not recommend it.
Accutane can effect healing and re-epithelialization of the skin. Placement of material in the lip should not in itself be a problem. However, the mere puncturing of the skin could conceivably lead to deleterious consequences and therein lies the remote chance. I would wait at least a month until the Accutane is well out of your system. Actually, it is out of your system after a few days, but this is a strange drug and its effects can last longer.
Interestingly, when Accutane first came out, back in 1980 I believe, I would sometimes receive referrals from plastic surgeons, to clear up their patient's acne before they performed ablative procedures such as dermabrasion. Never had a problem and in actuality these problems are rare.
However, when they do occur, they are disasterous. Severe scarring and the formation of excess heaped up skin called granulomas can ensue. Now the recommendation is to wait at least a year before any peeling or laser procedure.