You can use mesh fibreglas tape and waterproof joint compound. The really important part of this job is to install and caulk the liners properly, according to instructions. Greenboard is moisture RESISTANT but is in no way waterPROOF. If it gets wet on a regular basis, it is cooked.
By the way, there are special adhesives for attaching shower liners. Tub/tile caulk may be OK but I always use the adhesive recommended by the manufacturer. Usually "tub surround" by Liquid Nails. Whatever you do, DO NOT use regular Liquid Nails Project, Construction, or Subfloor.