The prerequisites are pretty clear: you must be a wizard, and you must have a spellbook.
Playing a regular Wizard would be the only way to get a spellbook (Hybrid Wizards don't get one), but there's a Swordmage feat, Student of Sword Magic from the Forgotten Realms Player's Guide (p136), which gives the Swordmage who takes it a Spellbook just like a Wizard.
There's also a Universal Option I'll describe farther down.
Your options if you can use this feat
Pick one thing to meet each prerequisite:
Fulfilling the Wizard prereq: Play a regular Wizard, play a Hybrid Wizard, or pick up a Wizard Multiclass Feat*.
Fulfilling the Spellbook prereq: Play a regular Wizard, or pick up Student of Sword Magic via playing a Swordmage or Hybrid Swordmage or picking up a Swordmage multiclass feat.
That boils down to a few combinations you can play with:
- Swordmage (regular or Hybrid) with SoSM and a Wizard Multiclass Feat*.
- Hybrid Wizard/Swordmage with SoSM.
- Hybrid Wizard with a Swordmage Multiclass feat and SoSM.
- Bard, with both Wizard and Swordmage Multiclass feats* and SoSM. Normally you can only pick one multiclass feat, but Bards can pick any amount thanks to Multiclass Versatility.
That last option affords you just enough room to be a bard with this theme, at the cost of three feats. Crucially, according to the Character Themes article on the WotC site, you can pick a theme at any level, and don't have to pick one at level one:
Your character can have only one theme, which you can choose when you create your character. The theme you select grants the benefits described in this section. You don't have to choose a theme, and you can defer your choice until you reach a higher level.
This means you can wait until you've acquired these feats, then choose that theme.
Your options if you cannot use this feat
Play a Wizard. Without Student of Sword Magic, there's no other way to get a Spellbook. Refluff your character to be bardlike.
The Universal Option
Play any kind of character you could reasonably imagine refluffing into a bard, and do so. D&D 4e encourages you to refluff non-mechanical descriptions of various effects into something that suits the character you want to play. If you're a Wizard, it's not unreasonable to say your Magic Missiles are the results of your mind-bending lute riffs that are beyond anyone's escape, so long as they both behave identically mechanically.
This stance on Flavor Text is described in the Rules Compendium on p93 (emphasis added):
The next entry in an adventurer power description, in italic text, briefly explains what the power does, from the perspective of the character. This material helps narrate what the power is doing in the game world. Players are free to invent their own descriptions of powers, sprinkling them with details specific to their adventurers or the campaign setting.
* That asterisk I keep using
It's not clear whether a Wizard Muticlass Feat means you count as a Wizard for the purpose of fulfilling theme prerequisites. The Player's Handbook says you count as a Wizard for the purpose of fulfilling prerequisites for feats or paragon paths, but that was before themes became a thing. It would make sense. It may be incongruous (a theme might suppose you were a Wizard all along), but D&D 4e encourages you to refluff any non-mechanical descriptions to suit your character.