it's a lincoln 5835 high freq box to tig weld with my ac/dc +/- lincoln arc welder

i found the manual online, but am unclear how to set this up....it has a watercooled tig torch, but i might convert it to a gas cooled torch

the unit looks like this:

http://cgi.ebay.com/LINCOLN-HI-FREQ-WELDER-5835-/290387183863?pt=BI_We lders

no...i didn't pay $500!...anyway could anyone give me some suggestions..

link to manual

http://content.lincolnelectric.com//...r/im/IM238.pdf

also...

convert arc to tig
...i've allready looked through all the posts on this subject (as well as on other internet sites) and wanted to ask some opinions

I am not a welder, but my father is quite good with oxyacet and arc...never used a mig or tig.. also his eyes are not what they used to be....
we will be attempting to repair some rust on an old alfa i have (have sheetmetal i cut from another car...wish me luck).....

1. I have a new (used once) lincoln ac/dc arc welder that i am going to try to do some tig welding with...it has ac and dc (+)(-)

anyway was wondering if anyone had any specific recommendations in regard to this specific unit.....(settings, named equipment, other tips)

as i said, thanks to this forum and others, i have a very good general idea on what to do....but am about to go out and buy what i need and wanted to check here before i do