If you can get your hands on the trans, it's definitely a do-able swap by yourself. Many manual swaps have been done on the FWD cars, and the AWD is pretty straightforward as well. As an added bonus, there are many people that can help you online if you decide to go forward with it, so you won't be alone.
Yup, plenty of people have done it. Member "Big Will" has a euro-market M58 5 speed manual in his 98 V70 AWD; and member "Lookforjoe" has swapped a newer M66 6 speed manual into his 98. "Bdub" from V70R.com recently swapped an M58 into his 98 R.