USB support isn't available natively in the pops mode because the usb.prx (required for any usb operation) was removed
by sony in the reboot sequence.
That's why i didn't put it's support in the previous release else cwcheat wouldn't load at all (missing imports)
From this release and upper you will have 2 version of the prx: one with usb support disabled which works without much work
and one with USB support (identified by the ending USB and which can be found in the root of the archive).

To make USB working there are two ways one more easy and safe and one more complicated and dangerous but definitive.
let's start with the easy way.

to do this you need:
-PSPFILER (i have the 1.50 version but the latests 2.x will surely work)
-cwcheat usb version
-enough space in ms for the usb.prx (26.2kb+)
-already installed the latest release of cwcheat without usb support
-303OE+
-a text editor (notepad or jed are fine)

let's start:
1-load pspfiler from 1.50 mode
2-press start till you see flash0:/
3-now scrool down till you see the kn folder
4-search there for usb.prx
5-Press x to open a menu and select to copy usb.prx to ramdisk with O
6-now press start till you are in ms0:/
7-scrool down to the seplugins folder and press /_\ (triangle) to copy all the files (usb.prx) from ramdisk
8-now you can exit and open the ms with the pc
9-copy cwcheatpops-USB.prx (or the one with cwcheatpops-cwcheatformat-USB.prx if you want it) to the seplugins
  folder and rename it as cwcheatpops.prx
10-open the pops.txt
11-you will see this:

ms0:/seplugins/cwcheatpops.prx


12-add before what you see ms0:/seplugins/usb.prx
13-now it should look like this:

ms0:/seplugins/usb.prx
ms0:/seplugins/cwcheatpops.prx


14-save & close and disconnect usb
15-power up your psp with R so it will enter recovery mode
16-go to plugins ->
17-scrool to usb.prx [POPS] (Disabled) and press X to enable it. if cwcheat is still not enabled enable also it
18-exit recovery
19-done now enjoy usb support while in pops :)

now we'll talk about the more dangerous way which requires flash0 writing but will be definitive (at least till 304+ :P).

to do this you need:
-PSPFILER (i have the 1.50 version but the latests 2.x will surely work)
-cwcheat usb version
-already installed the latest release of cwcheat without usb support
-303OE+
-a text editor (notepad or jed are fine)


let's start:
1-load pspfiler from 1.50 mode
2-press start till you see flash0:/
3-now scrool down till you see the kn folder
4-search for pspbtcnf_pops.txt
5-Press x to open a menu and select to copy pspbtcnf_pops.txt to ramdisk with O
6-now press start till you are in ms0:/
7-scrool down to the reflash folder and press /_\ (triangle) to copy all the files (pspbtcnf_pops.txt) from ramdisk
8-now you can exit and open the ms with the pc
9-open pspbtcnf_pops.txt and search for $/kd/openpsid.prx
10-do a new line and add $/kd/usb.prx
11-save and copy cwcheatpops-USB.prx (or the one with cwcheatpops-cwcheatformat-USB.prx if you want it) to the seplugins
   folder and rename it as cwcheatpops.prx and power off the psp
12-power on the psp in recovery mode with R
13-select Advanced->
14-select flash pspbtcnf_pops(3.03) option with x
15-if you havent enable cwcheatpops in the plugins menu
16-done now enjoy usb support while in pops :)