Managed to run swap via the init.d script.
Device working stably, applications open and do not crash.
To run swap, first of all you need this file
and SD card with Linux Swap partition on it (so you will have 2 ext4, 1 fat32 and 1 Linux Swap partitions). The best size of SWAP partition not yet determined, use 256-512 Mb for the fist time.
1. Unzip and place file "01swap" on Leo SD card. You may need to change "mmcblk0p2" parameter to "mmcblk0p1" or "mmcblk0p3" - it depends on your SD card and sets experimentally - until the SWAP is appear.
2. Install "Disk Info" program for checking the result -the SWAP partition must appear.
3. Specify 50% zRAM in preferences-perfomance and reboot.
4. After that, copy the previously prepared script "01swap" by Root Explorer to the system/ets/init.d and set permissions to 755. Device may crash or hang, wait some minutes and rebot it.
5. Use the Disk Info program to check SWAP is appear. Now we have enough "RAM" for stable work.
set zRAM to 0 or 10-20%. 50% + SWAP is not stable and not required.
Also, you may turn off "Kernel samepage merging", it may increase stability.