Do you mean fitting a Filter over a normal lamp?
I started out with a 'Lamping' set-up + IR Pass filter, it was pretty good as it had a Dimmer / rheostat (fabulous thing to use that, the variable power is brilliant for Hunting). However both the fit of the filter & the quality of the beam gave cause for concern - basically it was fairly visible (as well as being large) plus the trailing wires to the big battery were a PITA!!
I now own at least 8 LED IR lamps & 4 Laser IR..er.. lamps, they are purpose built, small & efficient.
If you do decide to try a conversion job make sure you are getting IR PASS Filter material & the stated pass point is for 780nm wavelength and above. Sadly all light, whether IR or not, can potentially damage your II tube.
Best of luck