I think you can just use basic 40% glycerol (in water). Glycerol is available from many sources. Use an equal volume of 40% glycerol to washed, packed red cells. Freeze @ -80 C is small aliquots. I don't remember the details of recovery, but it involves washing with a couple of different Saline concentrations, akin to deglycerolizing red cells for transfusion. The "Valeri Method" - see the article below.
Vox Sang 2000;79(3):168-74. An experiment with glycerol-frozen red blood cells stored at -80 degrees C for up to 37 years. C R Valeri 1, G Ragno, L E Pivacek, G P Cassidy, R Srey, M Hansson-Wicher, M E Leavy