How to print in base 2 a sequence of number

From: Alfonso Esteban Gonzalez Sencion (sencion_at_alcatel.es)
Date: 04/26/04 

Date: Mon, 26 Apr 2004 17:29:33 +0200

Hello all

How can I print a decimal string in binary using tcl

For example I would like to sprint the string

"123 120 12 45 68 123 123 456"

Into binary. Each number is an 8 bit unsigned value. That is

"01111011 01111000 00001100 00101101 01000100"

Thanks in advance