Converting data from 8 to 9.2

Dear CNC Gurus!

Need your advice please ->
At the moment we have two separate JDE - 9.2 on Win/SQL and 8 on AS/400 (live).
The goal is to convert data from 8 to 9.2 without standard upgrade procedure.
Our action plan is as follows:
1) Create a Pathcode/Environment in 9.2 and bulk copy old tables from 8 to it (using 3rd party tools)
2) Align 9.2 DD adding missing entries from 8 DD
3) Run (somehow) relevant TCs from upgrade installation plan against new Pathcode
4) Run relevant TCs that mentioned in 'Data-only upgrade' document

Constraint:
1) We cannot touch 8 setup

Questions:
a) Is our action plan more or less correct? What valuable is missing?
b) How we can implement p.3 above without messing with installation planner?

Would be happy to receive your feedback...

Thanks!
Yuri