Proton rocket with DM booster and Zond - a version of Soyuz spacecraft, without the orbital module - was launched multiple times in 1960s. DM adds about 3 km/s deltaV. Baikonur latitude is 46N, to get to 39N one needs to change orbital plane for 7 degrees, sin(7)*8 km/s is about 1 km/s. So there could be some options there.
If you launch from Baikonur directly into a 46° orbit, you will drop spent rocket stages on China. That is why the Russians launch into a 51° orbit, even though their launch site is at 46°.
With a Proton, you have enough delta-v to launch into 51° and then make a change of plane to 39°. But the Russians don't just have three Protons and three Soyuzes sitting around, ready to launch. They have to schedule these things.
The Soyuz is normally not launched on a Proton these days -- not since the 1970s. They'd have to jury-rig a bunch of things. It would not necessarily have been safer than a NASA Shuttle rescue.
