Please be aware the ISO disk image you linked to above must be burned to a CD-ROM, the OtherOS file you need is on the CD-ROM. Then, with the disk inserted, the PS3 XMB should then find the OtherOS file automatically when you attempt to install it.
If this knowledge doesn't help, could you please provide us with a bit more detail of the steps you took and where things went wrong. Please include any specific error messages.
Thanks for you bug report.
Please be aware the ISO disk image you linked to above must be burned to a CD-ROM, the OtherOS file you need is on the CD-ROM. Then, with the disk inserted, the PS3 XMB should then find the OtherOS file automatically when you attempt to install it.
If this knowledge doesn't help, could you please provide us with a bit more detail of the steps you took and where things went wrong. Please include any specific error messages.