The lanthanides can be represented by their fully ionized 3+ sparkles. That is, they have no basis set, and therefore cannot have a charge different from +3.000. To use these sparkles, add keyword SPARKLE.
The geometries of the lanthanides are reproduced with good accuracy, but the heats of formation and electronic properties are not accurate.
To specify AM1 Dysprosium 3+ ion, use keywords AM1 and SPARKLE, and specify Dy at the appropriate point in the Z-matrix.