1: open a command prompt
2: navigate to your xcom working folder (the folder that contains bb's modpack)
3: navigate to the bb_tact folder
4: run something along the lines of "pck2gif c:\path\to\xcom\UNITS\bigobs"
or copy bigobs.pck and bigobs.tab to the bb_tact folder and run
"pck2gif bigobs"
this will unpack the contents of the bigobs file to bb_tact\bigobs\
from here you can edit any files you need to, and if you want to add more files, use the same naming convention as what is laid out already.
5: after modifying/adding all the textures that you want, run "gif2pck bigobs"
this will re-pack the .pck file and update the index of the .tab file
6: copy the newly remade bigobs.pck and bigobs.tab to the \xcom\UNITS\ folder, and hey presto! you have your graphics available in-game.
the same method can be applied to just about any of the game's resource files, though some may require renaming (for example from .spk to .pck in rare cases)
note, that they will not show up unless there is a reference to them defined in the ruleset.
the numbers in the rulesets are NOT specific references to indexes in the PCKs, they are OFFSETS, so for example, if you wanted to make a new craft, you would need to use sprite offset 22 for the first available slot in the basebits, which would refer to the index basebits_54 (craft sprites start at 33 ) or to get to the same sprite as a base interior, you'd need to use offset 55, as they enumerate from the FIRST indexed position (0).
you may also need to pad files with blank entries, using craft as an example again, with a craft using sprite offset 22 (sprite 54 in basebits) you will need to pad the inticons.pck with 5 blank entries (i would use these slots for weapon icons), then the "minimized interception icon"(sprite 21 in inticons), then 10 more blank entries, then the "maximized interception icon"(sprite 32 in inticons). as you can see, this limits us to a maximum of 11 additional craft in a given mod, unless we use external pck files.
actually, scratch the limit. we'd just need to alternate between minimized and maximized icons every 11 files.
hope all this ranting helps.
