quick gamecube question about softmod and GCOS

ok so i have meh gamecube and want to mod it for linux *currently on ubuntu* ^^ and i was wonder if i got ahold of a copy of PSO and loaded the GCOS dol would i be able to just soft mod the cube so i could boot my brew from sd and stuff? the cheapest place to get a mod chip i found was Foundmy and its not in stock that i know of xS.. if i was able to do this would i have to do it every time i booted the cube up or just once? and if i cannot find a copy of PSO are there any other games i can use to softmod? sorry for being late to the parts >.< by almost 5 years .. just never figured i would do it but now i want to ^^