HI, Im wanting to bus it from Antigua to Cancun. I know its possible but unsure of the route and how long it takes. Any help would be great. Currently living in Honduras if anyone wants any tips.

Yes, it's quite possible. Here's what I recommend.

You travel Antigua - Guatemala City - Flores - Belice - Chetumal - Cancun. Each section can be purchased separately, as I'm sure you will want to stay over in Flores (Tikal) and Belice. Here's Linea Dorada's site, which are luxury buses. http://tikalmayanworld.com/about/index.htm

Guatemala - Flores is about 8 hours and costs about US$ 30.00
Flores - Belice is about 4 hours (plus about an hour at the border crossing). US$ 20.00
Belice - Chetumal is about 3 hours, plus about 30 mins at the border crossing. US$ 5.00
Not much to see in Chetumal.
Chetumal - Cancun is about 6 hours. US$ 20.00

All routes are daily, with 8 buses daily from Chetumal to Cancun.

Much lower cost if you take chicken buses. If you do decide on this budget option, for the Flores - Belice sections, take a bus from Flores to Melchor de Mencos, walk across the border and then take a local bus from there to Belize City.

There are no chicken buses in Mexico.

Bon Voyage!