persistence while multibooting different versions of tc on the same partition

[coreplayer2]

To some degree i have persistence on both, tce for backup and extension at least.  opt & home appear to be more challenging

During a slow transition to tc4.x I decided to keep tc3.8.4 active since it's the only method available to access the internet for now on a particular pc.  This means multi booting 3.8, 4.0 on one partition, trouble is I use persistent tce, home & opt directories and would like to keep all the relevant files for each tc version in their respective isolated directory.  which I've so far only been able to maintain with the older 3.8.4 frugal install and have temporarily moved all  but the home and opt directories to it's own separated directory (sda1/tc3).   the new tc4.x version is installed into it's own directory (sda1/tc4) along with it's boot and tce directories, unfortunately moving the opt and home directories is unsupported (or I'm doing it wrong again)

I'm sure I read in the wiki where we can specify a location of our choosing for both opt & home, however I have so far failed to accomplish this and also can no longer find the wiki page..    the boot codes to move tce directories to a desired location function great but I can't say the same for the opt and home directories.   Maybe I messed it up, but I distinctly remember reading only recently how moving the home & opt directories was a benefit of tc, I just can't find where is all.  Am looking because the page gave examples.

These bootcodes work in my boot config file for now (I use UUID's but for simplicity have shown them here as sda1)

Kernel /tc3/boot/bzimage -quiet tce=sda1/tc3 opt=sda1 home=sda1
initrd /tc3/boot/tinycore.gz
&
Kernel /tc4/boot/vmlinuz -quiet tce=sda1/tc4
initrd /tc4/boot/tinycore.gz

As I understand it, it may be possible to move both opt and home to a separate partition but I'd like to keep them in their respective tc3 & tc4 directories on the same partition along with their respective tce directories..

Am still searching, but thought someone may have come across persistence while multibooting different versions of tc on the same partition and maybe able to define what is possible and what isn't