Don't worry, I just found out that I haven't tested my own medicine thoroughly enough, because just adding bunch of java classes from 4.09 mod version is bound to create compatibility issues and crashes. So everyone please disregard my previous post - I was celebrating success too early!
After some further trials and errors I've managed to find a different, partially working solution. Nothing revolutionary, most of it has already been mentioned in one form or another in previous posts in this topic. So what MIGHT you achieve* if you follow steps listed below?
A) Working 64 channel sound which is handy to prevent sound cut-offs when lots of SFX are being played (unmodded Il-2 tops out at 32 channels which is far below modern standards 128 ch.)
B) Flyby sounds that are SLIGHTLY better than default HSFX 7.0.2 but still noticeably worse than HSFX 7.0.2 with jgsme 'TIGER Flyby's' mod activated.
C) As an unintended (?) side-effect of using tiger's SFS files I noticed that the
annoying echo-like reverb effect I used to get whenever I enabled EAX on my SB X-fi Titanium (through ALchemy since I've got Windows 8.1) is GONE! So that's a nice bonus (well, at least for me...)
Detailed 'How to' in a post below.
* Real life always gets in the way of proper testing, so I don't guarantee anything