You cannot update firmware without the full IDE runtime. However, you can copy the firmware .bin file to your portable drive and run the IDE from there.
For older PCO, PCOe, and PCO2 controllers, Carel provided PCO Manager (Classic). This is a simpler, text/block-based editor. While discontinued, many legacy systems still require it. carel pco programming software download portable
The software is useless without connecting to the PCO via a programming cable (usually Carel CAB series or TTL converter). You cannot update firmware without the full IDE runtime
This is the current graphical programming environment based on Codesys 2.3. It uses IEC 61131-3 languages (FBD, IL, ST, LD, SFC). If you are working with new-generation PCO3 or PCO5 controllers, this is your primary tool. For older PCO, PCOe, and PCO2 controllers, Carel
Instead of chasing a fragile "portable" hack, consider these professional solutions: