Its actually pretty simple just use Arsenal III to edit the unit.dat file heres what you do once your in it:
1. on the food and space if you want it infinite units change them to 0 for every unit.
2. go to advanced then you can edit properties that you can place em with ex. hollucionated buildings
3. go to miscellanious settings and edit the movement flags checking everything to put units anywhere
4. go to the staredit settings and make sure Owned, Placeable, Briefing, Player Settings, All Races, DONT CHECK PART OF TERRAIN, check this 1 unknown, Special Effect/Nuke, then leave everything else whatever its already set at or you could make something that crashes
5. edit the Group Flags while still in the staredit tab but leave the sublabel alone
6. go into the Graphics tab then edit the Unit Dimensions and Sel. Circle Dimensions changing the width and height to 1 then save your Unit.dat file as arr\units.dat
now for the tblpad part
1. if you do not have a english stat_txt.tbl file extract it from starcrafts mpqs and keep extracting differant ones in the list till you get the english version
2. once you got your file open it in tblpad you will notice how all the names have <0> in it thats mainly used for folders but it displays the folder to the right of the unit file
3. edit the folders you want all your units in to customize where their stored then once your finished save it as rez\stat_txt.tbl
now that your finished making it you just compile it with these steps
1. put all your modded files into a new mpq you make with winmpq
2. compile it into a mod but make it so the target file for them to patch is staredit
now test your editor
ADDITION: now if only I could explain it better and make it shorter I could make that a tutorial

ANOTHER ADDITION: Minerals dont matter just keep em and dont pay me anything