I haven't seen any info regarding getting PL3 working with the M:robe 100 so I thought I'd make a post about it seeing as it's what I use to jailbreak my PS3.

Download and install rockbox to your M:robe 100.

Get the pre-made package made by DanyL for your respective PS3 firmware. ie, 3.41, 3.15 or 3.01. Once you have this, copy it into the .rockbox folder on your M:robe and overwrite the existing rockbox.mi4.

Now to jailbreak your PS3, turn off the M:robe 100 and connect it to any USB port on the PS3 using the 'special' M:robe to USB cable that came with your M:robe. If your PS3 is a phat PS3, turn it off at the switch on the back of the console so that the red standby light turns off. Once the light turns off, flick the switch back on again so that the red light turns on again. If you have a slim PS3, instead of flicking the switch off and then on, you need to physically remove the power cable and then put it in again. This step has to be performed every time you turn the PS3 on, regardless of whether you are using a phat or slim PS3.

Once you've done the above, turn the M:robe 100 on, and as soon as the screen lights up push the power button on your PS3 once and then immediately push the eject button on your PS3 once. You'll know if the PS3 was successfully JB'd if the PS3 takes longer than normal to start up and if you see the option to install package files under the GAME section in the XMB.