If i understand your 'nibble' stuff...
Code:
WordA    Var Word
Nibble1  Var Byte
Nibble2  Var Byte
Nibble3  Var Byte
Nibble4  Var Byte

WordA=$1234
Nibble1=WordA.Highbyte>>4
Nibble2=WordA.Highbyte&$0F
Nibble3=WordA.LowByte>>4
Nibble4=WordA.Lowbyte&$0F