Variable: tex-alt-dvi-print-command

Command used by M-x tex-print with a prefix arg to print a .dvi file.
If this string contains an asterisk (`*'), that is replaced by the file name;
otherwise, the file name, preceded by blank, is added at the end.

If two printers are not enough of a choice, you can set the variable
`tex-alt-dvi-print-command' to an expression that asks what you want;
for example,

(setq tex-alt-dvi-print-command
'(format "lpr -P%s" (read-string "Use printer: ")))

would tell M-x tex-print with a prefix argument to ask you which printer to use.