bootloader for MH-tiny(Attiny88)

Hi.
i’ve got a MH-Tiny ATTiny88.
When the board is powered up,default bootloader waits 5 seconds to give a chance to upload a different program.but this delay is not good for my projects .
I’m looking for another bootloaders for my AtTiny88 to get rid of 5 second startup delay.
Is there any Tutorials for my situation?
thx for your help.

What would you prefer?

I think my ATTinyCore has option for 16MHz external clock w/out bootloader (iSP programming only) on the t88; if not I’ll add that for 1.4.0, which will be out in the next couple of days.

I suspect that one could built a serial bootloader (optiboot) for it, so it would behave like normal serial bootloader with e ternal USB serial adapter… (but not the built in VUSB usb port)