here was the thread way back when https://groups.google.com/forum/#!topic/vmsnet.pdp-11/0RZKjpVmIGQ
and http://www.dbit.com/pub/pdp11/rt11/putr.mac I'm still looking for my version of putr.mac but that should get you started. Most of the non PDP-11 tapes on bitsavers were read with this.
