I'm not familiar with the 'Visor' PDA and the OS and version of such but if your running the Palm OS 3.0 or earlier Omniremote has a free download of there Version 1.17 program. This is for the older Palm OS.
From the site;
OmniRemote v1.171 Supported Hardware
OmniRemote v1.171 supports "older" PalmOS hardware such as:
PalmPilot Personal
PalmPilot Professional
All Pilot models with an OS3.0 Upgrade Card
Palm III, IIIe, IIIe SE, IIIx, IIIxe, IIIc, V, Vx, VII
Some versions of the Palm VIIx
Handspring Visor Basic, Edge, Platinum, Prism, Pro, Neo
IBM Workpad 20x, 30x, c3, 50u, 50J
Symbol SPT1500, SPT1700, SPT1700-2D
TRG Pro
Omniremote Version 1.171
WB
EDIT, BTW, I have not tried this software as my PDA has the Palm 4.whaterever version. However, I would like to know how the OmniRemote app works out though. While the linked app is free the 'Pro' app (for newer Palm OS's) is $30 US. Maybe you could post back your exp. if you try the app.