We PC players do it 'cause we're used to the keyboard. =P
There are no cheat codes for the PC version of AO
except for "-ddcheat", but I think that only works with the full PC versions of AO and AE. A non-official view FMVs reward at the end of AO is given to you if you save all 99 muds in the full version, just like on the PSX.
In PC AO, you typically make Sligs shoot simply by pressing "Z" (or "Y" on German keyboards). The demo of AO only goes as far as the end of Rupture Farms, and the Rupture Farms level is very different to the full version, since mudokons are placed differently and there are no hidden areas.
Hope this helps.