Hello!
1) use original siemens software (for example MPM-Mobile Phone Manager) for upload java BootCore Patch midlet to phone
download this sof from [Only registered and activated users can see links. ] website.

here is java BootCore patch midlet (by Chaos):
version 1
PX65I.ZIP ==> Download it at support Area

if version 1 doesn't work, run version 2:
px65v2.zip ==> Download it at support Area

unzip it, and upload into phone, in java/Aplications directory.

2) power on phone without simcard
3) connect phone to program (SIEM Service Tools)
press "Simulate SIM-Card (x65 series)" function:

]
(Thanx for AcidMRP for sim simulator code).
This function will give you way to enter phone menu (like normal simcard).
Please enter "applications menu" and run java midlet
wait until phone automatic turn off, or show "===OK==="

4) please turn off phone (if didn't turn off automatically)
5) select on SIEM Service Tools "java (patched bootcore)" mode
6) sleect your phone type (for example C65)
7) press any functions you want

ATTENTION!
Before playing with phone, make EEprom backup (read EEprom zone).

Best Regards!