A20 and IDT

[Tom]

I did get the A20 working ( I think ) but when ever I do a a20 check it reboots

still need to know if idt is ok after pmode..

[grey wolf]

I do not know if you have solved your problem but I think there is a A20 enabling BIOS int. So before gonig into pmode you can call it to enable A20 line. I did not use it, (in fact I tried but for some reason it did not work ) You can find info on interrupt from:
http://www.ctyme.com/intr/int-15.htm
Also: Is this way a comvenient way to turn on a20? I mean is it alright if we enable it via bios int and then jump to pmode?

according to the page you referenced:

Also supported by AMI PCI BIOS and Qualitas 386MAX v6.01+. IBM classifies this function as optional

so, this function is not universal and can't be depended on. that's probably why it didn't work for you. it would be nice, though, if it was universal.