You have an FMCB 1.5 MC?
Copy the main-elf of "ule" to the root of your USB-Stick and rename it to "RESCUE.ELF" (all UPPERCASE and without the "quotes").
When ule is executed, just browse to the folder where you unpacked the Nooby-package.
Install it and you´re fine.
I suggest you to install FMCB 1.8 to another MC, than the FMCB 1.5-MC (you don´t need to...).
PS2 V7/DMS3 V2 (FW:2.4b7); Seagate Baracuda 200GB
PS2 V7/CC1.0 (FW:34 hacked v2 BM:2.1.6); Maxtor DiamondMAX9 PLUS 160GB
PS2 SCPH-30004R; NoMod+NoLaser
3xSony MC 8MB
MAX/Datel 16MB with Boot-CD
Custom FMCB 1.8b+ Beta-Build, my AIO 0.5, Sony&xRhino-Linux