generic instruction

   I need a pseudo instruction that can carry a variable number -
still a small number b/w 2-6 - of immediate values. I have two
different uses for such an instruction

1. I one scenario, they translate to immediate moves after register allocation
2. In a different one, they carry information about other
non-immediate operands.

Short of declaring different formats in the td for each case, is there
a generic way to carry such information, say an index perhaps ?

thanks for any pointers