looks like it can be done with a rtl dongle. http://www.youtube.com/watch?v=yxJthBDQXTM
R70 uses same IF scheme as the R71. The rear Scope terminal has the 70.4515Mhz IF. Plug RTL antenna port into the Scope output, tune RTL to 70.4515MHz, enjoy. No mods needed. Just a $25 dongle, SDR# and your pc.