can i update ipt firmware without being online?

[Ipodnoob356]

hii again!! it me the noob. i know you can update ur ipod touch maunlly by holding down shift and pressing restore or update on itunes but i need to know if its possible to do this with out interet. i already have the ipsw saved on my desktop. but my coumputer has no internet and cant go online so im wondering if i can update my ipod touch 2g on firmware 3.1.2 to 4.2.1 with being online and if its not possible is their another way i can do update without using itunes. o and my ipod touch is jailbroken.

[Patato22]

You need to be online couse itunes need to connect to the server.