Help with v1.5..GPS not working?

I am using a v1.5 psp, and using the version. I copied the mapviewer and mapviewer% from the 1.5 folder into my psp games folder. I updated the system file as well as the eboot in the mapviewer% with the one found in the v0.499. Then created a map using the gmdl (but without "no gpsfs" box checked), and I am able to view it on mapthis!. I bought the psp 290, but somehow i don't think its working, for when I turn GPS on, theres no signal nor any fix. The moment i move the cursor the gps turns off by itself. Could it be that I'm using a 1.5? I heard from other (older) threads that 1.5 won't work, but I can see my map clearly.

1st use the Green Screen Tool if your PP-290 is working.
http://www.dcemu.co.uk/vbulletin/showthread.php?t=70041

you'll need to run it under 3.xx kernel...
upgrade to any custom firmware..

Im afraid it does not work. It says i need the prx files in the camprx folder. So even for v1.5, and using a psp 290, i still need the prx files?

Which custom firmware is suggested? I don't want to end up with a custom fw which will not allow my to use the psp 290 properly. Which cfw is most recommended (and easiest).