Can I have a Hair transplant if I have sebum excess (that causes hairloss) in the donor area?

It is possible but you need an examination of your donor hair. Having excess sebum is not an issue with hair transplant surgery.  It is about getting an examination to make sure you are a candidate for surgery.

Since it has been 5 years since you took Accutane, you should have no problem having a hair restoration procedure. The main things that need to be evaluated to determine if you are a good candidate for the procedure are: 1) density of the hair growth in the donor area. Do you have enough hair to transplant without the donor area becoming sparse. 2) is the vascular supply to the recipient area sufficient and are there any other things that may impair the growth of the transplanted follicles. An exam by a surgeon that is experienced in hair restoration is important for the best advice. Good luck!

Hair loss and Accutane go hand in hand. If you have been off this drug for jore than a year then you can have a hair transplant. 

if your Accutane therapy was years ago, i cannot see that as interfering with the outcome of a hair tansplant. If you are having ongoing therapy, discuss this with your surgeon.